feat(analytics): add optional Aptabase event tracking UI

Integrate Aptabase analytics via a Tauri plugin and add a privacy
notice flow plus a settings dialog to control whether anonymous
usage events are sent. The app now tracks key user actions while
ensuring analytics never blocks core Git operations.

- Add analytics tracking helper and Aptabase plugin wiring
- Persist analytics consent in localStorage and gate tracking
- Introduce notice and settings dialogs, plus new event calls

src-tauri/build.rs

@@ -1,3 +1,4 @@
 fn main() {
+    println!("cargo:rerun-if-env-changed=APTABASE_KEY");
     tauri_build::build();
 }