refactor: 统一权限检查逻辑，使用 apiKeyService.hasPermission

将散布在各处的权限检查逻辑（permissions || 'all'）统一为
apiKeyService.hasPermission() 方法调用，确保：

- 权限检查的唯一真实来源
- 避免默认值不一致导致的安全问题
- 便于后续权限模型的扩展和维护

影响文件：
- geminiHandlers.js: key-info 端点
- apiStats.js: user-stats 统计端点
- openaiClaudeRoutes.js: 权限校验辅助函数
- openaiRoutes.js: key-info 端点

src/routes/openaiClaudeRoutes.js

@@ -20,8 +20,7 @@ const { getEffectiveModel } = require('../utils/modelHelper')
 
 // 🔧 辅助函数：检查 API Key 权限
 function checkPermissions(apiKeyData, requiredPermission = 'claude') {
-  const permissions = apiKeyData.permissions || 'all'
-  return permissions === 'all' || permissions === requiredPermission
+  return apiKeyService.hasPermission(apiKeyData?.permissions, requiredPermission)
 }
 
 function queueRateLimitUpdate(rateLimitInfo, usageSummary, model, context = '') {