fix: disable Redis RDB persistence to resolve overcommit_memory warning

Redis in LXC/Proxmox cannot change kernel vm.overcommit_memory.
Disabling RDB saves eliminates the warning with no functional impact
(Redis used only for heartbeat TTL cache, not persistent storage).

docker-compose.yml

@@ -20,6 +20,7 @@ services:
 
   redis:
     image: redis:7-alpine
+    command: redis-server --save "" --appendonly no
     volumes:
       - redisdata:/data
     ports: