feat(windows): Phase 6 C2 — close-to-tray + Settings toggle 持久化

- ui/settings-page.slint: SettingsToggleRow 的 toggled callback
  从 (bool) 改成 (string, bool) — 把 row 自己的 label + 新 value
  一起交给 caller；row 内部先 value=!value 再 emit；value 改
  in-out property 让内部可以 flip；SettingsPage 加 callback
  toggle-persist(string, bool)；7 个真 toggle 全部 wire 到
  toggle-persist（Notifications 4 + Startup 3）
- ui/app.slint: MainWindow 加 in-out property ×7 +
  setting-toggled(string, bool) callback；启动从 ActiveConfig
  装载；SettingsPage section 把 7 个 property forward 给 page +
  toggle-persist 转接到 root.setting-toggled
- src/lib.rs:
  · 启动从 ActiveConfig 读 7 个 toggle 设到 MainWindow
  · 新 on_setting_toggled 回调：load AppConfig → 按 label 改
    对应字段 → save_config；start_with_windows 额外调
    startup::set_enabled 写 HKCU Run（Phase 6 C1）
  · on_close_requested 看 close_to_tray：true 时
    window().hide() + KeepWindowShown；false 时保持原来的
    HideWindow 行为

避坑：
- Slint 1.x callback 不能直接用 label 区分，必须 caller 传
  string 参数；改造 (bool) → (string, bool)
- 设置 in-out property 让 row 内部能 flip value 然后 emit
  新值（caller 收到的就是 post-flip 值）
- close_to_tray 在 UI MainWindow 上是 in-out property，Rust
  端用 get_close_to_tray() 实时读，所以 toggle 立刻影响
  close_requested 行为（不需要重启）
- on_close_requested 内部读 get_close_to_tray 要 upgrade()
  MainWindow weak handle，捕获空时 fallback false（默认
  close 而不是 hide）

验证：cargo build / build --release 都 exit 0，0 warning
- cargo test: 15 passed; 0 failed
- debug   35.64 MB, subsystem = WINDOWS_CUI
- release  9.78 MB, subsystem = WINDOWS_GUI

ui/app.slint

@@ -61,6 +61,21 @@ export component MainWindow inherits Window {
     // Rust persists it into `state.json::last_theme`.
     callback appearance-changed-persist(int);
 
+    // ── Phase 6 C2: live AppConfig toggles (Settings page) ─────────
+    // Forwarded from SettingsPage so the Rust runtime can:
+    //   1. Persist into `config.json`
+    //   2. For `start_with_windows`, also write HKCU Run.
+    //   3. For `close_to_tray`, immediately affect the close-requested
+    //      handler below without a restart.
+    in-out property <bool> desktop-notify: true;
+    in-out property <bool> sound: true;
+    in-out property <bool> notify-high: true;
+    in-out property <bool> notify-max: true;
+    in-out property <bool> start-with-windows: false;
+    in-out property <bool> start-minimized: false;
+    in-out property <bool> close-to-tray: true;
+    callback setting-toggled(string, bool);
+
     // ── Phase 3 C2: live connection status ───────────────────────
     in-out property <bool> is-connected: false;
     in-out property <string> status-text: "Disconnected";
@@ -210,6 +225,13 @@ export component MainWindow inherits Window {
 
             if root.selection == SidebarSelection.Settings: SettingsPage {
                 appearance-index: root.appearance-index;
+                desktop-notify: root.desktop-notify;
+                sound: root.sound;
+                notify-high: root.notify-high;
+                notify-max: root.notify-max;
+                start-with-windows: root.start-with-windows;
+                start-minimized: root.start-minimized;
+                close-to-tray: root.close-to-tray;
                 appearance-changed(idx) => {
                     root.appearance-index = idx;
                     root.theme = idx == 0 ? AppearanceMode.System :
@@ -220,6 +242,9 @@ export component MainWindow inherits Window {
                 test-connection-requested => {
                     root.test-connection-requested();
                 }
+                toggle-persist(label, value) => {
+                    root.setting-toggled(label, value);
+                }
             }
 
             // About entry stays as a simple right-pane marker; the