Phase 3.1: OSS storage config management (MinIO/AliyunOSS/AWS S3)

Backend:
- Add OSSStorageConfig model (models.py)
- Create storage_admin.py API (9 endpoints): stats, CRUD, toggle, set-default, test connection
- Register route /app/api/admin/storage in main.py
- Create oss_storage_configs table in MySQL

Frontend:
- Add Storage.tsx admin page (713 lines) with stats, table, create/edit modal
- Register /admin/storage route in App.tsx
- Add nav item and icon in AdminLayout.tsx
- Add 9 API methods in api/index.ts

frontend/src/api/index.ts

@@ -498,6 +498,20 @@ export const adminAPI = {
   checkAdminKnowledgeExtStatus: (id: string) => get<any>(`/admin/knowledge/external/services/${id}/status`),
   syncAdminKnowledge: (kbId: string, data: any) => post<any>(`/admin/knowledge/external/sync/${kbId}`, data),
   batchDeleteAdminKnowledge: (ids: string[]) => post<any>('/admin/knowledge/batch/delete', ids),
+  // OSS存储配置 (Phase 3.1)
+  getAdminStorageStats: () => get<any>('/admin/storage/stats/overview'),
+  getAdminStorageConfigs: (params?: any) => {
+    const query = params ? '?' + Object.entries(params).filter(([_, v]) => v !== undefined && v !== '').map(([k, v]) => `${k}=${v}`).join('&') : '';
+    return get<any>(`/admin/storage/${query}`);
+  },
+  getAdminStorageConfig: (id: string) => get<any>(`/admin/storage/${id}`),
+  createAdminStorageConfig: (data: any) => post<any>('/admin/storage/', data),
+  updateAdminStorageConfig: (id: string, data: any) => put<any>(`/admin/storage/${id}`, data),
+  deleteAdminStorageConfig: (id: string) => del<any>(`/admin/storage/${id}`),
+  toggleAdminStorageConfig: (id: string) => put<any>(`/admin/storage/${id}/toggle`),
+  setDefaultAdminStorageConfig: (id: string) => put<any>(`/admin/storage/${id}/set-default`),
+  testAdminStorageConfig: (data: any) => post<any>('/admin/storage/test', data),
+
 };
 // ===== AI自进化API =====
 export const evolutionAPI = {