fix(groups): 字节序排序按方言——MySQL CAST AS BINARY / SQLite COLLATE BINARY

collate("BINARY") 被 SQLAlchemy 反引号成标识符致 MySQL 500;SQLite 的
CAST AS BINARY 语义不符(排序键失效退化 room_id 序,测试失去判别力)。
按 session.bind.dialect 分支,两库都用真字节序。

726 测试绿。

Co-Authored-By: Claude Code <noreply@anthropic.com>

yunke-server/app/api/routers/groups.py

@@ -104,11 +104,20 @@ async def list_groups(
     if (channel or "wechat") == "wechat":
         # 云客「微信群统计」同款排序(2026-09-10 真机终判):owner_account_id
         # (=微信号/wxid 混存,如 Nancyjade < csf7169708 < wxid_01gv…——大写
-        # 在小写前=区分大小写)**二进制字符串升序**分组,组内 room_id 字符串
-        # 升序。COLLATE BINARY 双库通用(MySQL/SQLite)。WA 保持最近活跃优先。
+        # 在小写前=区分大小写)**二进制字节序升序**分组,组内 room_id 字符串
+        # 升序。字节序按方言:MySQL 用 CAST(col AS BINARY)(collate("BINARY")
+        # 会被 SQLAlchemy 反引号成标识符);SQLite 用 COLLATE BINARY(其 CAST
+        # AS BINARY 语义不符)。WA 保持最近活跃优先。
+        dialect = session.bind.dialect.name if session.bind is not None else ""
+        if dialect == "mysql":
+            owner_order = sa.literal_column(
+                "CAST(chat_group.owner_account_id AS BINARY)"
+            ).asc()
+        else:
+            owner_order = ChatGroup.owner_account_id.collate("BINARY").asc()
         list_stmt = (
             list_stmt.order_by(
-                ChatGroup.owner_account_id.collate("BINARY").asc(),
+                owner_order,
                 ChatGroup.room_id.asc(),
             )
             .limit(page_size)