feat(api): /api/sessions 账号会话列表(好友+群,今日消息数+最近联系时间,全本地聚合)

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

yunke-server/app/api/main.py

@@ -45,6 +45,7 @@ from app.api.routers import (
     messages,
     organization,
     search,
+    sessions,
     sms,
     staff_chat_stats,
     sync,
@@ -69,6 +70,7 @@ app.include_router(sms.router)
 app.include_router(staff_chat_stats.router)
 app.include_router(sync.router)
 app.include_router(search.router)
+app.include_router(sessions.router)
 app.include_router(export.router)