feat: 实现 Phase 1 — Bootstrap（Slint hello window + 编译验证通过）

完成 AGENTS.md §57 Phase 1 的全部交付：可编译的 Cargo 工程、能打开的
Slint hello window、release profile、Windows subsystem、tracing 日志、
thiserror 错误框架。`cargo build` 与 `cargo build --release` 均通过，
0 warning。

实现概览
--------

新增 / 修改的文件：

  src/lib.rs           lib crate 入口；`slint!{}` 内嵌一个最小 AppWindow
                       （标题 "Gotify"，480×320，深灰背景 + 两行文本）；
                       `pub fn run() -> AppResult<()>` 调 AppWindow::new
                       + run()。
  src/main.rs          thin binary entry；含
                       `#![cfg_attr(not(debug_assertions),
                          windows_subsystem = "windows")]`
                       让 release build 不弹 console（AGENTS.md §43）；
                       debug build 保留 console 让 tracing 日志可见。
  src/error.rs         `AppError` + `AppResult`，thiserror 2.0.20；Phase 1
                       只有 `Logging(String)` 与 `Ui(String)` 两个变体，
                       §24 的 ConfigError / NetworkError / WebSocketError
                       / StorageError / WindowsError / ParseError 等后续
                       Phase 落地时再加。
  src/logging.rs       `init_logging()`：tracing-subscriber 0.3.23，启
                       env-filter feature；debug 默认 debug 级，release
                       默认 info 级，`RUST_LOG` 可覆盖；关闭 ANSI（release
                       通常没有真实终端）。符合 §25 的"默认不记录消息正文"
                       基线——具体红线靠代码 review 强制。
  Cargo.toml           实际可编译的 manifest：[[bin]] 指向 src/main.rs；
                       仅引入 Phase 1 真正用到的依赖（slint / tracing /
                       tracing-subscriber / thiserror）；reqwest /
                       tungstenite / serde / url / anyhow 等推迟到对应
                       Phase 的模块创建后再引入——避免提前下载无用 crate，
                       也让 AGENTS.md §44 的 "Cargo 依赖最小化原则" 落到
                       每一阶段的 commit 上。
  Cargo.lock           已生成（564 个 transitive deps，含 slint 1.18.0、
                       skia-bindings、accesskit、parley、fontique 等）。
                       二进制工程，lock 文件进 git——保证可重现构建。

技术选型说明
------------

- Slint 版本选择：AGENTS.md §1 写的是 "Slint 1.17.x 或当前稳定兼容版
  本"。首次尝试钉死 `slint = { version = "1", features =
  ["internal-interpreter"] }`，cargo 报 `internal-interpreter` feature 不
  存在（slint 1.18.0 已移除该 feature，slint!{} macro 走 default feature
  set 即可）。改为 `slint = "1"`，cargo 自动选到 1.18.0，与 Rust 1.98.1 +
  MSVC 工具链编译通过。AGENTS.md §1 的措辞明确允许"当前稳定兼容版本"，
  本次选 1.18.0 不偏离约束。
- release profile：opt-level=z / lto / codegen-units=1 / panic=abort /
  strip=true（AGENTS.md §42 模板）。Phase 1 未做 benchmark，所以 release
  vs release-balanced 的实际选择留到 Phase 8 Performance。
- 没引 slint-build / 没建 build.rs：Phase 1 hello window 内嵌在
  `slint!{}` macro 里，足以通过验收。Phase 2 切到独立 .slint 文件 +
  `include_slint!()` 时再决定是否需要 build.rs。

验证结果
--------

  cargo build          exit 0, 5.21s（增量；首次冷编译约 1m40s，要编
                                  i-slint-core / parley / skia 等）
  cargo build --release exit 0, 1m38s（profile 内 LTO 阶段耗时长）
  warnings             0
  debug   .exe         25.58 MB, PE subsystem = 3 (WINDOWS_CUI / console)
  release .exe          7.82 MB, PE subsystem = 2 (WINDOWS_GUI)

AGENTS.md §57 Phase 1 验收标准（`cargo run` + `cargo build --release`
能打开无 console 的 Windows GUI）全部满足。PE subsystem 通过直接读
Optional Header 的 Subsystem 字段验证——而不是盲目信任 cfg_attr。

下一步
------

进 Phase 2 — UI Shell（MainWindow / Sidebar / Message list / Empty
state / Settings / Dark-Light-System 主题）。本阶段仍然只用 mock 消息，
不接网络。

遗留
----

- commit message 之前那条 root commit (`a3a6a7c`) subject 前有个 UTF-8
  BOM (`\ufeff`)，是 PowerShell 5.1 `Set-Content -Encoding UTF8` 默认带
  BOM 造成的。本 commit 用 `[System.IO.File]::WriteAllText` 直接写
  UTF-8 without BOM，新 commit 不再带 BOM；老的那个根 commit 的 BOM 只
  是显示瑕疵，不影响任何 git 操作，留着不重写。
- 首次 cargo build 拉了 564 个 crate、走代理拉取成功（crates.io 直连也
  通，HTTPS_PROXY 走 127.0.0.1:7890 是兜底）。
- target/ 1.4 GB 在 .gitignore 内，不会进 git。
- 用户的 .cargo/bin 不在 PowerShell 当前 session 的 PATH 上（用 rustup
  默认安装路径 `C:\Users\Administrator\.cargo\bin`），后续 cargo 命令
  脚本里临时加 PATH 即可，未修改用户全局环境。

src/error.rs

@@ -0,0 +1,27 @@
+//! Top-level application error type.
+//!
+//! The full taxonomy in AGENTS.md §24 is
+//! `ConfigError / NetworkError / WebSocketError / StorageError /
+//!  WindowsError / ParseError`, plus user-facing variants derived from them.
+//! Only the categories reachable in the current phase are wired up here; new
+//! variants land in later phases.
+
+use thiserror::Error;
+
+pub type AppResult<T> = std::result::Result<T, AppError>;
+
+/// Application-wide error.
+///
+/// All variants carry a `String` payload in Phase 1 because the upstream
+/// errors we propagate are themselves heterogeneous (tracing init, Slint,
+/// later reqwest/tungstenite). When the corresponding Phase adds a dedicated
+/// module, the String is replaced with a structured error from that module
+/// and the `From` impl is added.
+#[derive(Debug, Error)]
+pub enum AppError {
+    #[error("logging initialization failed: {0}")]
+    Logging(String),
+
+    #[error("ui error: {0}")]
+    Ui(String),
+}

src/lib.rs

@@ -0,0 +1,57 @@
+//! Windows Gotify Client (Rust) — core library.
+//!
+//! Phase 1 only exposes the bare-minimum surface needed to spin up the
+//! Slint hello window:
+//!   - [`error`]:  AppError / AppResult
+//!   - [`logging`]: tracing-subscriber init
+//!   - [`run`]:    entry that builds the Slint UI and runs its event loop
+//!
+//! Larger subsystems (gotify, storage, windows integration, ...) are added in
+//! later phases per AGENTS.md §57.
+
+pub mod error;
+pub mod logging;
+
+use slint::ComponentHandle;
+
+slint::slint! {
+    export component AppWindow inherits Window {
+        title: "Gotify";
+        width: 480px;
+        height: 320px;
+        background: #1f2024;
+
+        VerticalLayout {
+            padding: 24px;
+            spacing: 12px;
+
+            Text {
+                text: "Windows Gotify Client (Rust)";
+                color: #e6e6e6;
+                font-size: 18px;
+            }
+
+            Text {
+                text: "Phase 1 — Bootstrap OK";
+                color: #8a8a8a;
+                font-size: 12px;
+            }
+        }
+    }
+}
+
+/// Build the Slint UI and run its event loop until the window is closed.
+///
+/// In release builds the Windows subsystem is set to `windows` via the
+/// `#[cfg_attr]` on the binary entry point, so no console window is shown.
+pub fn run() -> AppResult<()> {
+    tracing::info!(
+        "starting windows-gotify-client-rust v{}",
+        env!("CARGO_PKG_VERSION")
+    );
+
+    let ui = AppWindow::new().map_err(|e| AppError::Ui(e.to_string()))?;
+    ui.run().map_err(|e| AppError::Ui(e.to_string()))
+}
+
+pub use error::{AppError, AppResult};

src/logging.rs

@@ -0,0 +1,29 @@
+//! Logging bootstrap — `tracing` + `tracing-subscriber`.
+//!
+//! Policy (AGENTS.md §25):
+//!   - Debug builds default to `debug` level.
+//!   - Release builds default to `info` level.
+//!   - Message bodies and tokens MUST NOT be logged (enforced by code review,
+//!     not by this module).
+//!   - Override at runtime with the `RUST_LOG` env var.
+
+use crate::error::{AppError, AppResult};
+use tracing_subscriber::{fmt, EnvFilter};
+
+/// Initialize the global tracing subscriber.
+///
+/// Idempotent at the type level — repeated calls fail with `AppError::Logging`
+/// (tracing only allows one global subscriber per process). That is intentional:
+/// the caller should call exactly once during startup.
+pub fn init_logging() -> AppResult<()> {
+    let default_level = if cfg!(debug_assertions) { "debug" } else { "info" };
+    let filter = EnvFilter::try_from_default_env()
+        .unwrap_or_else(|_| EnvFilter::new(default_level));
+
+    fmt()
+        .with_env_filter(filter)
+        .with_target(false)
+        .with_ansi(false)
+        .try_init()
+        .map_err(|e| AppError::Logging(e.to_string()))
+}

src/main.rs

@@ -0,0 +1,12 @@
+// Windows GUI application: release builds hide the console window entirely.
+// Debug builds keep the console so logs from `tracing` are visible.
+//
+// See AGENTS.md §43.
+#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
+
+use windows_gotify_client_rust::{logging, AppResult};
+
+fn main() -> AppResult<()> {
+    logging::init_logging()?;
+    windows_gotify_client_rust::run()
+}