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

package.json

@@ -1,7 +1,10 @@
 {
   "name": "gongxue-base",
   "private": true,
-  "workspaces": ["apps/*", "packages/*"],
+  "workspaces": [
+    "apps/*",
+    "packages/*"
+  ],
   "scripts": {
     "dev": "turbo run dev",
     "build": "turbo run build",
@@ -10,6 +13,12 @@
     "format": "turbo run format",
     "typecheck": "turbo run typecheck"
   },
-  "devDependencies": { "turbo": "^2.0.0" },
-  "dependencies": { "@fission-ai/openspec": "^1.5.0" }
+  "devDependencies": {
+    "oxfmt": "^0.57.0",
+    "oxlint": "^1.72.0",
+    "turbo": "^2.0.0"
+  },
+  "dependencies": {
+    "@fission-ai/openspec": "^1.5.0"
+  }
 }