fix: 卸载Agent后清除Redis心跳（之前只清MySQL导致在线状态残留）

卸载Agent后只更新MySQL is_online=False，但前端读Redis覆盖为True。
修复: uninstall_agent_remote + batch_uninstall_agent 都增加redis.delete(heartbeat:{id})

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

server/api/servers.py

@@ -824,6 +824,12 @@ async def batch_uninstall_agent(
                 ok = r["exit_code"] == 0
 
                 if ok:
+                    # Clear Redis heartbeat (real-time source) + MySQL
+                    try:
+                        redis = get_redis()
+                        await redis.delete(f"{REDIS_KEY_PREFIX}{sid}")
+                    except Exception:
+                        pass
                     server.is_online = False
                     server.agent_version = None
                     await db.commit()
@@ -1250,7 +1256,12 @@ async def uninstall_agent_remote(
             detail=f"卸载失败: {_install_error_msg(result.get('stdout', ''), result.get('stderr', ''), result['exit_code'])}",
         )
 
-    # Clear agent metadata in database
+    # Clear agent metadata: Redis (real-time source) + MySQL (history)
+    try:
+        redis = get_redis()
+        await redis.delete(f"{REDIS_KEY_PREFIX}{id}")
+    except Exception:
+        logger.warning(f"Failed to clear Redis heartbeat for server {id}", exc_info=True)
     server.is_online = False
     server.agent_version = None
     await db.commit()