fix(tauri): own Windows CLI subtree with a job object (#320)

## Summary
- Follow-up to #240 to make Windows desktop shutdown reliable this time,
even when the tracked CLI wrapper PID exits before its descendants
- Attach the spawned CLI process to a Windows Job Object with
`KILL_ON_JOB_CLOSE`, so the desktop app owns the whole subtree instead
of relying only on `taskkill /PID <wrapper> /T`
- Keep the current graceful-then-force shutdown path, but add a robust
OS-level fallback that reaps orphaned workspace processes when the
wrapper is already gone

## Root Cause
The previous Windows shutdown logic still depended on the PID tracked by
Tauri. In practice that PID can be a short-lived Node wrapper. Once that
wrapper exits, `taskkill` can report success or PID-not-found while
descendants remain alive, and the desktop app no longer has a reliable
handle to reap them.

## Validation
- `cargo check --manifest-path packages/tauri-app/src-tauri/Cargo.toml`
- `cargo build --release --manifest-path
packages/tauri-app/src-tauri/Cargo.toml`
- Manual local test: orphaned processes are cleaned up after desktop
shutdown

packages/tauri-app/src-tauri/Cargo.toml

@@ -28,4 +28,4 @@ url = "2"
 tauri-plugin-notification = "2"
 
 [target.'cfg(windows)'.dependencies]
-windows-sys = { version = "0.59", features = ["Win32_UI_Shell"] }
+windows-sys = { version = "0.59", features = ["Win32_Foundation", "Win32_UI_Shell", "Win32_Security", "Win32_System_JobObjects"] }