feat(auth-files): add antigravity quota cards with grouping, pagination, and i18n

src/i18n/locales/en.json

@@ -357,6 +357,15 @@
     "models_excluded_badge": "Excluded",
     "models_excluded_hint": "This model is excluded by OAuth"
   },
+  "antigravity_quota": {
+    "title": "Antigravity Quota",
+    "empty_title": "No Antigravity Auth Files",
+    "empty_desc": "Upload an Antigravity credential to view remaining quota.",
+    "loading": "Loading quota...",
+    "load_failed": "Failed to load quota: {{message}}",
+    "missing_auth_index": "Auth file missing auth_index",
+    "empty_models": "No quota data available"
+  },
   "vertex_import": {
     "title": "Vertex JSON Login",
     "description": "Upload a Google service account JSON to store it as auth-dir/vertex-<project>.json using the same rules as the CLI vertex-import helper.",

src/i18n/locales/zh-CN.json

@@ -357,6 +357,15 @@
     "models_excluded_badge": "已排除",
     "models_excluded_hint": "此模型已被 OAuth 排除"
   },
+  "antigravity_quota": {
+    "title": "Antigravity 额度",
+    "empty_title": "暂无 Antigravity 认证",
+    "empty_desc": "上传 Antigravity 认证文件后即可查看额度。",
+    "loading": "正在加载额度...",
+    "load_failed": "额度获取失败：{{message}}",
+    "missing_auth_index": "认证文件缺少 auth_index",
+    "empty_models": "暂无额度数据"
+  },
   "vertex_import": {
     "title": "Vertex JSON 登录",
     "description": "上传 Google 服务账号 JSON，使用 CLI vertex-import 同步规则写入 auth-dir/vertex-<project>.json。",