feat(task3): migrate toolchain to oxfmt + oxlint

- Install oxfmt with .oxfmtrc.json (maps Prettier config)
- Install oxlint with oxlint.config.ts (TypeScript + React rules)
- Replace admin ESLint with oxlint
- Remove Prettier integration from server ESLint (keep ESLint for type checking)
- Delete server .prettierrc and admin eslint.config.js

apps/server/package.json

@@ -7,7 +7,7 @@
   "license": "UNLICENSED",
   "scripts": {
     "build": "nest build",
-    "format": "prettier --write \"src/**/*.ts\" \"test/**/*.ts\"",
+    "format": "oxfmt",
     "start": "nest start",
     "start:dev": "nest start --watch",
     "start:debug": "nest start --debug --watch",
@@ -59,11 +59,8 @@
     "@types/passport-local": "^1.0.38",
     "@types/supertest": "^7.0.0",
     "eslint": "^9.18.0",
-    "eslint-config-prettier": "^10.0.1",
-    "eslint-plugin-prettier": "^5.2.2",
     "globals": "^17.0.0",
     "jest": "^30.0.0",
-    "prettier": "^3.4.2",
     "source-map-support": "^0.5.21",
     "supertest": "^7.0.0",
     "ts-jest": "^29.2.5",