feat(docker-compose.yml): add VITE_PROXY_TARGET environment variable to frontend service

feat(frontend/dev.Dockerfile): change npm start command to npm run dev:docker
feat(frontend/package.json): add dev:docker script to run vite with host 0.0.0.0
feat(frontend/vite.config.ts): use environment variable to determine the target for proxying requests

docker-compose.yml

@@ -17,6 +17,8 @@ services:
       dockerfile: ./dev.Dockerfile
       args:
         - BACKEND_URL=http://backend:7860
+    environment:
+      - VITE_PROXY_TARGET=http://backend:7860
     ports:
       - "3000:3000"
     volumes: