Improve docker setup

- add .dockerignore to reduce build context
- add entrypoint.sh to initialize environment before user switch
- fix Celery setting deprecation warnings
- downgrade importlib-metadata for Celery compatibility
- set TZ environment variable for consistent Celery timestamps

entrypoint.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+set -e
+
+su -c /srv/gvamysql.sh gvamysql