refactor: 全局适配 ApiFamily/EndpointKind 结构化标识体系

将新的 (ApiFamily, EndpointKind) / `family:kind` 签名体系应用到整个代码库：
- API Handlers: 所有 adapter/handler 使用新的签名格式
- Services: provider, model, usage, cache, auth 等服务层适配
- Database: ProviderEndpoint 新增 api_family/endpoint_kind 字段
- Frontend: Provider 管理、Usage 表格等组件适配
- Tests: 更新所有相关测试用例

src/api/monitoring/user.py

@@ -2,21 +2,21 @@
 
 from __future__ import annotations
 
-from typing import Any
 from dataclasses import dataclass
 from datetime import datetime, timedelta, timezone
+from typing import Any
 
 from fastapi import APIRouter, Depends, HTTPException, Query, Request
 from sqlalchemy.orm import Session
 
 from src.api.base.adapter import ApiAdapter, ApiMode
+from src.api.base.context import ApiRequestContext
 from src.api.base.pagination import PaginationMeta, build_pagination_payload, paginate_query
 from src.api.base.pipeline import ApiRequestPipeline
 from src.core.logger import logger
 from src.database import get_db
 from src.models.database import ApiKey, AuditLog
 from src.plugins.manager import get_plugin_manager
-from src.api.base.context import ApiRequestContext
 
 router = APIRouter(prefix="/api/monitoring", tags=["Monitoring"])
 pipeline = ApiRequestPipeline()