chore: add engineering improvements

- Configure Prettier with unified code style rules
- Add husky + lint-staged for automated pre-commit checks
- Add commitlint to enforce conventional commit messages
- Add PR check workflow for CI automation
- Auto-format all files with Prettier
- Fix TypeScript any types in field-crypto.ts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

package.json

@@ -20,7 +20,8 @@
     "build:linux-appimage": "npm run build && electron-builder --linux AppImage",
     "build:linux-targz": "npm run build && electron-builder --linux tar.gz",
     "test:encryption": "tsc -p tsconfig.node.json && node ./dist/backend/backend/utils/encryption-test.js",
-    "migrate:encryption": "tsc -p tsconfig.node.json && node ./dist/backend/backend/utils/encryption-migration.js"
+    "migrate:encryption": "tsc -p tsconfig.node.json && node ./dist/backend/backend/utils/encryption-migration.js",
+    "prepare": "husky"
   },
   "dependencies": {
     "@codemirror/autocomplete": "^6.18.7",
@@ -105,6 +106,8 @@
     "zod": "^4.0.5"
   },
   "devDependencies": {
+    "@commitlint/cli": "^20.1.0",
+    "@commitlint/config-conventional": "^20.0.0",
     "@eslint/js": "^9.34.0",
     "@types/better-sqlite3": "^7.6.13",
     "@types/cors": "^2.8.19",
@@ -123,9 +126,20 @@
     "eslint-plugin-react-hooks": "^5.2.0",
     "eslint-plugin-react-refresh": "^0.4.20",
     "globals": "^16.3.0",
+    "husky": "^9.1.7",
+    "lint-staged": "^16.2.3",
     "prettier": "3.6.2",
     "typescript": "~5.9.2",
     "typescript-eslint": "^8.40.0",
     "vite": "^7.1.5"
+  },
+  "lint-staged": {
+    "*.{js,jsx,ts,tsx}": [
+      "eslint --fix",
+      "prettier --write"
+    ],
+    "*.{json,css,md}": [
+      "prettier --write"
+    ]
   }
 }