refactor(frontend): 迁移 ESLint 到 flat config 格式

- 移除旧版 .eslintrc.cjs 和 .eslintignore
- 新增 eslint.config.js 使用 flat config 格式
- 更新相关依赖版本

frontend/package.json

@@ -11,7 +11,7 @@
     "test": "vitest",
     "test:ui": "vitest --ui",
     "test:run": "vitest run",
-    "lint": "eslint . --ext .vue,.js,.jsx,.cjs,.mjs,.ts,.tsx,.cts,.mts --fix --ignore-path .eslintignore",
+    "lint": "eslint . --fix",
     "type-check": "vue-tsc --noEmit"
   },
   "dependencies": {
@@ -38,6 +38,7 @@
     "vue-router": "^4.5.1"
   },
   "devDependencies": {
+    "@eslint/js": "^9.39.1",
     "@types/node": "^24.3.3",
     "@typescript-eslint/eslint-plugin": "^8.47.0",
     "@typescript-eslint/parser": "^8.47.0",
@@ -53,6 +54,7 @@
     "tailwindcss": "^3.4.17",
     "tailwindcss-animate": "^1.0.7",
     "typescript": "~5.8.3",
+    "typescript-eslint": "^8.49.0",
     "vite": "^7.1.2",
     "vitest": "^4.0.10",
     "vue-tsc": "^3.0.5"