feat: add Supabase auth config to production Docker setup

- Pass SUPABASE_JWT_SECRET to backend in docker-compose.prod.yml
- Add build args (VITE_API_URL, VITE_SUPABASE_URL, VITE_SUPABASE_ANON_KEY)
  to Dockerfile.prod so Vite inlines them at build time
- Pass build args from secrets in deploy workflow
- Add build section to frontend service in docker-compose.prod.yml

No GoTrue container needed in prod — Supabase Cloud hosts the auth
service. The backend only needs the JWT secret to verify tokens.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/deploy.yml

@@ -28,6 +28,9 @@ jobs:
       - name: Build and push frontend image
         run: |
           docker build --platform linux/amd64 \
+            --build-arg VITE_API_URL=${{ secrets.VITE_API_URL }} \
+            --build-arg VITE_SUPABASE_URL=${{ secrets.VITE_SUPABASE_URL }} \
+            --build-arg VITE_SUPABASE_ANON_KEY=${{ secrets.VITE_SUPABASE_ANON_KEY }} \
             -t gitea.nerdboden.de/thefurya/nuzlocke-tracker-frontend:latest \
             -f frontend/Dockerfile.prod ./frontend
           docker push gitea.nerdboden.de/thefurya/nuzlocke-tracker-frontend:latest