新增: 后台会话系统通知与托盘运行态

- 完成/失败/需介入三类系统通知,主窗聚焦静默
- 同类通知五秒合并,用户主动停止不通知
- 托盘菜单与悬浮提示实时显运行中会话数
- 关窗遇运行会话提示后台续跑,每进程一次
- 侧栏常驻徽章显后台运行会话数

src-tauri/Cargo.toml

@@ -18,6 +18,9 @@ tauri = { version = "2", features = ["tray-icon"] }
 tauri-plugin-dialog = "2"
 tauri-plugin-opener = "2"
 tauri-plugin-window-state = "2"
+# P1 bg 化补完:系统通知。AI 完成/失败/需介入三类事件,主窗隐藏到托盘时补位提醒,
+# Rust 侧条件发送(notify.rs):主窗可见聚焦不发 + 同类 5 秒节流 + 失败静默
+tauri-plugin-notification = "2"
 # Phase3 单实例:二次启动唤起已有进程主窗口,防多实例抢 18765 端口
 tauri-plugin-single-instance = "2"
 serde.workspace = true