refactor: 重构活跃请求查询逻辑到 UsageService

- 在 UsageService 新增 get_active_requests 方法，统一处理活跃请求查询
- 支持自动清理超时的 pending 请求（默认 5 分钟）
- admin 和 user 接口均复用该方法，减少重复代码
- 支持按 ID 列表查询或查询所有活跃请求

src/api/admin/usage/routes.py

@@ -651,42 +651,17 @@ class AdminActiveRequestsAdapter(AdminApiAdapter):
         self.ids = ids
 
     async def handle(self, context):  # type: ignore[override]
-        db = context.db
+        from src.services.usage import UsageService
 
+        db = context.db
+        id_list = None
         if self.ids:
-            # 查询指定 ID 的请求状态
             id_list = [id.strip() for id in self.ids.split(",") if id.strip()]
             if not id_list:
                 return {"requests": []}
 
-            records = (
-                db.query(Usage.id, Usage.status, Usage.input_tokens, Usage.output_tokens, Usage.total_cost_usd, Usage.response_time_ms)
-                .filter(Usage.id.in_(id_list))
-                .all()
-            )
-        else:
-            # 查询所有活跃请求（pending 或 streaming）
-            records = (
-                db.query(Usage.id, Usage.status, Usage.input_tokens, Usage.output_tokens, Usage.total_cost_usd, Usage.response_time_ms)
-                .filter(Usage.status.in_(["pending", "streaming"]))
-                .order_by(Usage.created_at.desc())
-                .limit(50)
-                .all()
-            )
-
-        return {
-            "requests": [
-                {
-                    "id": r.id,
-                    "status": r.status,
-                    "input_tokens": r.input_tokens,
-                    "output_tokens": r.output_tokens,
-                    "cost": float(r.total_cost_usd) if r.total_cost_usd else 0,
-                    "response_time_ms": r.response_time_ms,
-                }
-                for r in records
-            ]
-        }
+        requests = UsageService.get_active_requests(db=db, ids=id_list)
+        return {"requests": requests}
 
 
 @dataclass