fix: Docker Compose working configuration

Major fixes to Docker setup:
- Fix frontend Dockerfile path (Dockerfile not Dockerfile.frontend)
- Remove obsolete version attribute from docker-compose.yml
- Add --legacy-peer-deps to npm ci for dependency resolution
- Fix Celery commands to use uv run celery
- Change frontend port from 3000 to 8888 (avoid conflicts)

Services now starting (with some configuration issues to resolve):
- PostgreSQL: Running on port 5432
- Redis: Running on port 6379
- Frontend: Running on port 8888
- Backend/Celery: Starting but having DB connection issues

Known issues to fix:
- Backend connecting to localhost instead of postgres service
- Environment variables not properly passed to containers

docker-compose.yml

@@ -46,7 +46,7 @@ services:
       dockerfile: Dockerfile.backend
     container_name: mockupaws-celery-worker
     restart: unless-stopped
-    command: celery -A src.core.celery_app worker --loglevel=info --concurrency=4
+    command: uv run celery -A src.core.celery_app worker --loglevel=info --concurrency=4
     environment:
       DATABASE_URL: postgresql+asyncpg://postgres:postgres@postgres:5432/mockupaws
       REDIS_URL: redis://redis:6379/0
@@ -69,7 +69,7 @@ services:
       dockerfile: Dockerfile.backend
     container_name: mockupaws-celery-beat
     restart: unless-stopped
-    command: celery -A src.core.celery_app beat --loglevel=info
+    command: uv run celery -A src.core.celery_app beat --loglevel=info
     environment:
       DATABASE_URL: postgresql+asyncpg://postgres:postgres@postgres:5432/mockupaws
       REDIS_URL: redis://redis:6379/0
@@ -92,7 +92,7 @@ services:
       dockerfile: Dockerfile.backend
     container_name: mockupaws-flower
     restart: unless-stopped
-    command: celery -A src.core.celery_app flower --port=5555 --url_prefix=flower
+    command: uv run celery -A src.core.celery_app flower --port=5555 --url_prefix=flower
     environment:
       CELERY_BROKER_URL: redis://redis:6379/1
       CELERY_RESULT_BACKEND: redis://redis:6379/2
@@ -150,7 +150,7 @@ services:
     environment:
       VITE_API_URL: http://localhost:8000
     ports:
-      - "3000:80"
+      - "8888:80"
     depends_on:
       - backend
     networks: