Add script to build and push Docker images to registry

- Introduced `push-images.sh` script for building and pushing backend and frontend images.
- Added functionality to select or input image tags.
- Integrated environment variable support for registry configuration.
- Implemented prompts for user confirmation before building and pushing images.
- Updated `docker-compose.prod.yml` with new image tags after pushing.

docker-compose.prod.yml

@@ -0,0 +1,22 @@
+services:
+  backend:
+    image: git.danielvolz.org/daniel/medassist/backend:0.0.1
+    env_file:
+      - .env
+    volumes:
+      - ./backend/data:/app/data
+    ports:
+      - "4000:3000"
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:3000/health"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 10s
+
+  frontend:
+    image: git.danielvolz.org/daniel/medassist/frontend:0.0.1
+    ports:
+      - "4174:80"
+    depends_on:
+      - backend