feat(permissions): 服务权限从单选改为多选

- 将 API Key 的服务权限从单选改为多选，支持同时选择多个服务
- 移除"全部服务"选项，空数组表示允许访问全部服务
- 后端自动兼容旧格式（'all' -> [], 'claude' -> ['claude']）
- 前端 radio 改为 checkbox，更新账户选择器联动逻辑

修改文件：
- apiKeyService.js: 添加 normalizePermissions/hasPermission 函数
- api.js, droidRoutes.js, openaiRoutes.js, unified.js, openaiGeminiRoutes.js, geminiHandlers.js: 使用新权限验证函数
- admin/apiKeys.js: 支持数组格式权限验证
- CreateApiKeyModal.vue, EditApiKeyModal.vue: UI 改为 checkbox 多选

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/routes/unified.js

@@ -8,6 +8,7 @@ const {
   handleStreamGenerateContent: geminiHandleStreamGenerateContent
 } = require('../handlers/geminiHandlers')
 const openaiRoutes = require('./openaiRoutes')
+const apiKeyService = require('../services/apiKeyService')
 
 const router = express.Router()
 
@@ -73,7 +74,7 @@ async function routeToBackend(req, res, requestedModel) {
     return await openaiRoutes.handleResponses(req, res)
   } else if (backend === 'gemini') {
     // Gemini 后端
-    if (permissions !== 'all' && permissions !== 'gemini') {
+    if (!apiKeyService.hasPermission(permissions, 'gemini')) {
       return res.status(403).json({
         error: {
           message: 'This API key does not have permission to access Gemini',