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/capabilities/default.json

@@ -11,6 +11,7 @@
     "core:window:allow-close",
     "core:window:allow-is-maximized",
     "core:window:allow-start-dragging",
-    "dialog:allow-open"
+    "dialog:allow-open",
+    "aptabase:allow-track-event"
   ]
 }