perf: 优化 MySQL 查询并接入 pytest

web/backend/routers/accounts.py

@@ -126,7 +126,7 @@ def list_accounts(
 
     total = None
     if page is not None:
-        total = query.order_by(None).count()
+        total = query.order_by(None).with_entities(func.count(Account.id)).scalar() or 0
     query = query.order_by(Account.id)
     if page is not None:
         query = query.offset((page - 1) * page_size).limit(page_size)
@@ -173,13 +173,18 @@ def accounts_summary(
         else:
             raise HTTPException(status_code=403, detail="无权查看账号")
 
-    total = query.count()
-    assigned_count = query.filter(Account.assigned_to.isnot(None)).count()
+    total = query.with_entities(func.count(Account.id)).scalar() or 0
+    assigned_count = (
+        query.filter(Account.assigned_to.isnot(None))
+        .with_entities(func.count(Account.id))
+        .scalar()
+        or 0
+    )
     tag_count = (
         query.filter(Account.tag != "", Account.tag.isnot(None))
-        .with_entities(Account.tag)
-        .distinct()
-        .count()
+        .with_entities(func.count(func.distinct(Account.tag)))
+        .scalar()
+        or 0
     )
     return {
         "total": total,