feat(a11y): add focus lock dependency and useDialogFocus hook

- Install react-focus-lock@2.13.7 for focus trap functionality
- Create useDialogFocus hook with focus management, Escape key handling,
  initial focus, focus restoration, and body scroll lock
- Create E2E test infrastructure with helper functions for focus testing
- Compatible with React 19 and Electron 39

package.json

@@ -42,6 +42,7 @@
     "mysql2": "^3.18.2",
     "playwright": "^1.58.2",
     "playwright-core": "^1.58.2",
+    "react-focus-lock": "^2.13.7",
     "reflect-metadata": "^0.2.2",
     "typeorm": "^0.3.28",
     "uuid": "^13.0.0",