feat(FN-1074): add desktop tray and application menu

- Add dedicated desktop tray and menu modules, including platform-aware menu templates and tray status/visibility controls
- Integrate tray setup, app menu initialization, and tray status exports into the Electron main process bootstrap
- Add tray icon assets plus an icon generation script and update desktop package dependencies/lockfile
- Expand desktop test coverage with new menu/tray test suites and main process integration assertions
- Update desktop README with tray and application menu usage/documentation

packages/desktop/package.json

@@ -12,6 +12,7 @@
     "build": "tsc",
     "test": "vitest run",
     "typecheck": "tsc --noEmit",
+    "generate:icons": "tsx scripts/generate-icons.ts",
     "pack": "electron-builder",
     "dist": "electron-builder --publish never"
   },
@@ -43,6 +44,7 @@
     "@vitest/coverage-v8": "^3.1.0",
     "electron": "^35.0.0",
     "electron-builder": "^26.0.0",
+    "sharp": "^0.33.0",
     "tsx": "^4.19.0",
     "typescript": "^5.7.0",
     "vitest": "^3.1.0"