Initial implementation of Claude desktop app (Tauri v2)

Standalone native desktop app wrapping claude.ai with:
- Direct webview navigation to claude.ai (not iframe)
- System tray with close-to-tray behavior
- Native notification bridge (JS overrides browser Notification API)
- Navigation filter allowing only Claude, Anthropic, and OAuth domains
- External links open in system browser
- Session persistence via WebKitGTK cookies/localStorage
- Builds .deb and AppImage bundles

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    tauri_build::build();
+}