Add production Dockerfile for backend deployment

README.md

@@ -12,6 +12,29 @@ psql "$DATABASE_URL" -f scripts/init_schema.sql
 ./scripts/start_dev.sh
 ```
 
+## Docker (VPS / Production)
+
+Build image:
+```bash
+cd backend
+docker build -t memberapi-backend:latest .
+```
+
+Run container:
+```bash
+docker run -d \
+  --name memberapi-backend \
+  --restart unless-stopped \
+  -p 127.0.0.1:8000:8000 \
+  --env-file .env \
+  memberapi-backend:latest
+```
+
+Health check:
+```bash
+curl http://127.0.0.1:8000/healthz
+```
+
 ## Keycloak env
 
 - Required: