fix(ui): Phase 7 C4 — 卡片间距修复 + 全 UI 翻译为简体中文

两个问题修一处：\n\n1. 布局 bug：filter 切到 Max/High/Normal/Low 后可见卡片之间留出巨大空白。原因：Slint isible: false 在 for 循环里没真正折叠 layout 槽位，被隐藏的卡片仍占 76px 高 + 8px spacing。修法：把过滤从 Slint 侧搬到 Rust 侧，新增 filtered_model：UI 绑 filtered_model，shared_model 作为全量 canonical；切换过滤时 rebuild_filtered_model + WS drain 用 push_message_to_models 同步两表；测试连接 / tray restart 也都双表更新。\n\n2. UI 默认中文：sidebar（MESSAGES/SERVERS/FILTERS/APP → 消息/服务器/过滤/应用；All/Max/High/Normal/Low/Settings/About → 全部/最高/高/普通/低/设置/关于）、详情面板（Open link → 打开链接）、空态（You're all caught up → 暂时没有新消息；Test Notification → 发送测试通知）、设置页（5 个分组 + 所有 toggle + Appearance radio）、AboutDialog、托盘菜单（打开/暂停通知/设置.../重新连接/退出/新消息：N）、状态文本（Disconnected → 未连接；mock feed → 模拟数据；messages → 条消息）。\n\n新增 priority-filter-changed(int) 回调，sidebar 切过滤时通知 Rust 重建 filtered model。SharedModel/FilteredModel 同步逻辑：HTTP catch-up → WS drain push → 测试连接 → tray restart 都用 helper 函数维护一致性。

src/lib.rs

@@ -70,6 +70,49 @@ fn theme_str(m: AppearanceMode) -> &'static str {
     }
 }
 
+/// Phase 7 C4: rebuild `filtered_model` from `shared_model` based on
+/// the current priority filter. `priority_filter` matches the Slint
+/// encoding (0 = all, 1..4 = Low/Normal/High/Max). Used at startup,
+/// on each filter change, and on each refetch. Cheap enough at our
+/// scale (≤ a few hundred messages in V1) to rebuild fully instead
+/// of tracking diffs.
+fn rebuild_filtered_model(
+    shared: &Rc<VecModel<MessageItem>>,
+    filtered: &Rc<VecModel<MessageItem>>,
+    priority_filter: i32,
+) {
+    let items = shared.iter().filter(|m| match priority_filter {
+        1 => m.priority == Priority::Low,
+        2 => m.priority == Priority::Normal,
+        3 => m.priority == Priority::High,
+        4 => m.priority == Priority::Max,
+        _ => true, // 0 or unknown = show all
+    }).collect::<Vec<_>>();
+    filtered.set_vec(items);
+}
+
+/// Push a freshly-arrived WS message into both models in one go.
+/// Honors the active priority filter so the filtered_model doesn't
+/// drift out of sync with the canonical shared_model.
+fn push_message_to_models(
+    shared: &Rc<VecModel<MessageItem>>,
+    filtered: &Rc<VecModel<MessageItem>>,
+    item: MessageItem,
+    priority_filter: i32,
+) {
+    let matches = match priority_filter {
+        1 => item.priority == Priority::Low,
+        2 => item.priority == Priority::Normal,
+        3 => item.priority == Priority::High,
+        4 => item.priority == Priority::Max,
+        _ => true,
+    };
+    shared.push(item.clone());
+    if matches {
+        filtered.push(item);
+    }
+}
+
 /// Build the MainWindow and run its event loop until the window is closed.
 pub fn run() -> error::AppResult<()> {
     tracing::info!(
@@ -118,12 +161,18 @@ pub fn run() -> error::AppResult<()> {
     ui.set_start_minimized(cfg.start_minimized);
     ui.set_close_to_tray(cfg.close_to_tray);
 
-    // ── Phase 7 C2: long-lived message model. We bind `ui.messages`
-    // to this single VecModel once and update it via `set_vec` on
-    // every fetch so the WS drain keeps pushing into the same model
-    // even after a refetch. ──
+    // ── Phase 7 C2 + C4: message models. `shared_model` is the
+    // canonical full feed (every message we've seen). `filtered_model`
+    // is what `ui.messages` actually binds to — it mirrors shared_model
+    // but only includes items matching the current `priority-filter`
+    // (0 = all). Rebuilding this on every filter change / message
+    // arrival / refetch fixes the layout bug where Slint's `visible:
+    // false` on for-loop items doesn't actually collapse layout slots
+    // (see user screenshot: cards stretched to fill vertical space,
+    // big empty gaps between filtered items). ──
     let shared_model: Rc<VecModel<MessageItem>> = Rc::new(VecModel::default());
-    ui.set_messages(ModelRc::from(shared_model.clone()));
+    let filtered_model: Rc<VecModel<MessageItem>> = Rc::new(VecModel::default());
+    ui.set_messages(ModelRc::from(filtered_model.clone()));
 
     // ── Phase 7 C1+C2: tray icon (Windows only). Created up-front so
     // the WS drain closure can capture an `Arc<TrayIcon>` and call
@@ -278,7 +327,7 @@ pub fn run() -> error::AppResult<()> {
                     "gotify: HTTP fetch failed; using mock data, WS worker skipped"
                 );
                 shared_model.set_vec(models::mock_messages());
-                status_text = format!("Disconnected · mock feed · {}", server.base_url);
+                status_text = format!("未连接 · 模拟数据 · {}", server.base_url);
                 is_connected = false;
                 ws_credential = None;
             }
@@ -286,21 +335,32 @@ pub fn run() -> error::AppResult<()> {
         None => {
             tracing::info!("no server configured; mock feed only");
             shared_model.set_vec(models::mock_messages());
-            status_text = "No server configured · mock feed".to_string();
+            status_text = "未配置服务器 · 模拟数据".to_string();
             is_connected = false;
             ws_credential = None;
         }
     }
 
+    // Phase 7 C4: rebuild filtered model from the freshly-populated
+    // shared_model. Filter state is 0 (all) right after startup; the
+    // callback wired below keeps it consistent on user changes.
+    rebuild_filtered_model(&shared_model, &filtered_model, 0);
+
+    // Phase 7 C4: shared cell holding the current priority filter.
+    // Used by the WS drain, the refetch path, and the priority-filter
+    // callback. Lives in `Rc<RefCell>` so multiple closures (drain,
+    // priority-filter-changed, test_connection) can all read+write
+    // it on the UI thread.
+    let priority_filter_cell: Rc<RefCell<i32>> = Rc::new(RefCell::new(0));
+
     ui.set_status_text(status_text.into());
     ui.set_is_connected(is_connected);
 
-    // ── Phase 4 C2 + 5 C2 + 7 C1/C2: WebSocket worker + UI-thread
-    // drain. The drain closure also fires a desktop toast for each
-    // new message via the tray's `show_toast` (any thread → the tray
-    // helper window's WndProc, which is the only thread allowed to
-    // call Shell_NotifyIconW), and now also services the
-    // `restart_requested` flag set by the tray's on_restart. ──
+    // ── Phase 4 C2 + 5 C2 + 7 C1/C2 + 7 C4: WebSocket worker + UI-thread
+    // drain. The drain closure now writes to BOTH the canonical
+    // shared_model AND the filtered_model (honoring the active
+    // filter), so the UI sees exactly the right set of cards without
+    // Slint having to do the filtering itself. ──
     let drain_timer = if let Some((base_url, token, apps)) = ws_credential {
         let (tx, rx) = mpsc::channel::<MessageItem>();
         let apps_by_id: std::collections::HashMap<i64, gotify::GotifyApplication> =
@@ -323,11 +383,15 @@ pub fn run() -> error::AppResult<()> {
             .map_err(|e| error::AppError::Gotify(format!("ws thread spawn: {e}")))?;
 
         let timer = slint::Timer::default();
-        let model_for_drain = shared_model.clone();
+        // Phase 7 C4: drain closure now writes to both shared_model
+        // (canonical) and filtered_model (UI-bound, priority-aware).
+        let shared_for_drain = shared_model.clone();
+        let filtered_for_drain = filtered_model.clone();
         let state_for_drain = state_rc.clone();
         let tray_for_drain = tray_arc.clone();
         let tray_state_for_drain = tray_state_for_ws.clone();
         let ui_handle_for_drain = ui.as_weak();
+        let filter_cell_for_drain = priority_filter_cell.clone();
         timer.start(
             slint::TimerMode::Repeated,
             std::time::Duration::from_millis(100),
@@ -391,7 +455,12 @@ pub fn run() -> error::AppResult<()> {
                                     tray.show_toast(&title, &body, icon_flags);
                                 }
                             }
-                            model_for_drain.push(item);
+                            push_message_to_models(
+                                &shared_for_drain,
+                                &filtered_for_drain,
+                                item,
+                                *filter_cell_for_drain.borrow(),
+                            );
                         }
                         Err(_) => break,
                     }
@@ -418,9 +487,14 @@ pub fn run() -> error::AppResult<()> {
                             None,
                         ) {
                             Some((apps, msgs, text)) => {
-                                model_for_drain.set_vec(
+                                shared_for_drain.set_vec(
                                     models::gotify_messages_to_items(&msgs, &apps),
                                 );
+                                rebuild_filtered_model(
+                                    &shared_for_drain,
+                                    &filtered_for_drain,
+                                    *filter_cell_for_drain.borrow(),
+                                );
                                 if let Some(ui) = ui_handle_for_drain.upgrade() {
                                     ui.set_status_text(text.into());
                                     ui.set_is_connected(true);
@@ -487,7 +561,9 @@ pub fn run() -> error::AppResult<()> {
     // ── Phase 3 C2 + 7 C2: Settings → Connection → Test button ───
     ui.on_test_connection_requested({
         let ui_handle = ui.as_weak();
-        let model_for_test = shared_model.clone();
+        let shared_for_test = shared_model.clone();
+        let filtered_for_test = filtered_model.clone();
+        let filter_cell_for_test = priority_filter_cell.clone();
         move || {
             tracing::info!("settings: Test Connection clicked");
             let Some(server) =
@@ -497,9 +573,14 @@ pub fn run() -> error::AppResult<()> {
             };
             match models::try_fetch_initial_data(&server.base_url, &server.token, None) {
                 Some((apps, msgs, text)) => {
-                    model_for_test.set_vec(
+                    shared_for_test.set_vec(
                         models::gotify_messages_to_items(&msgs, &apps),
                     );
+                    rebuild_filtered_model(
+                        &shared_for_test,
+                        &filtered_for_test,
+                        *filter_cell_for_test.borrow(),
+                    );
                     if let Some(ui) = ui_handle.upgrade() {
                         ui.set_status_text(text.into());
                         ui.set_is_connected(true);
@@ -509,7 +590,7 @@ pub fn run() -> error::AppResult<()> {
                 None => {
                     if let Some(ui) = ui_handle.upgrade() {
                         ui.set_status_text(
-                            format!("Disconnected · mock feed · {}", server.base_url).into(),
+                            format!("未连接 · 模拟数据 · {}", server.base_url).into(),
                         );
                         ui.set_is_connected(false);
                     }
@@ -609,6 +690,24 @@ pub fn run() -> error::AppResult<()> {
         }
     });
 
+    // ── Phase 7 C4: priority-filter-changed callback. The Slint
+    // sidebar's "全部 / 最高 / 高 / 普通 / 低" rows fire this when
+    // tapped; we update the shared filter cell and rebuild the
+    // filtered model so the visible cards immediately match the
+    // user's selection. The Slint property `priority-filter` is
+    // still set by the click handler (drives the sidebar highlight);
+    // this callback runs alongside it. ──
+    ui.on_priority_filter_changed({
+        let shared_for_filter = shared_model.clone();
+        let filtered_for_filter = filtered_model.clone();
+        let filter_cell_for_filter = priority_filter_cell.clone();
+        move |filter: i32| {
+            tracing::info!(filter, "sidebar: priority filter changed");
+            *filter_cell_for_filter.borrow_mut() = filter;
+            rebuild_filtered_model(&shared_for_filter, &filtered_for_filter, filter);
+        }
+    });
+
     // ── Phase 2 C3 / 5 C2 / 6 C2: save state on OS-close ──────────
     // Phase 6 C2: when `close_to_tray` is true, hide the window and
     // pretend to honor the close (return `KeepWindowShown`); otherwise