feat: configure docker image deployment with Gitea Container Registry

- Replace local build with pre-built image from Gitea registry
- Add docker-compose.override.yml for local development with Dockerfile
- Add .dockerignore to exclude unnecessary files from build
- Update image reference to gitea.onecluster.org/oneteam/don_confiao_backend:latest

Refs #37

docker-compose.yml

@@ -1,8 +1,6 @@
 services:
   django:
-    build:
-      context: ./
-      dockerfile: django.Dockerfile
+    image: gitea.onecluster.org/oneteam/don_confiao_backend:latest
     env_file:
       - .env
     volumes: