feat(ui): add comprehensive quality gates and fix linting issues

- Added ESLint, Prettier, TypeScript strict mode to ui/ directory
- Fixed 40+ lint/format issues across ui codebase
- Created extraction files for react-refresh compliance:
  - button-variants.ts for Button component styles
  - use-sidebar.ts, use-websocket-context.ts custom hooks
  - ws-context.ts WebSocket context provider
- Fixed React hooks issues (setState ordering, dependency arrays)
- Added ui:validate script to enforce quality checks
- Updated husky pre-commit to validate UI files on change

ui/package.json

@@ -6,7 +6,12 @@
   "scripts": {
     "dev": "vite",
     "build": "tsc -b && vite build",
+    "typecheck": "tsc -b --noEmit",
     "lint": "eslint .",
+    "lint:fix": "eslint . --fix",
+    "format": "prettier --write src/",
+    "format:check": "prettier --check src/",
+    "validate": "bun run typecheck && bun run lint:fix && bun run format:check",
     "preview": "vite preview"
   },
   "dependencies": {
@@ -40,9 +45,11 @@
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^5.1.1",
     "eslint": "^9.39.1",
+    "eslint-config-prettier": "^10.1.8",
     "eslint-plugin-react-hooks": "^7.0.1",
     "eslint-plugin-react-refresh": "^0.4.24",
     "globals": "^16.5.0",
+    "prettier": "^3.6.2",
     "tailwindcss": "^4.1.17",
     "typescript": "~5.9.3",
     "typescript-eslint": "^8.46.4",