fix: Correct production deployment to use pre-built Docker images

CRITICAL: This fixes the deployment issue where changes weren't appearing on production

Changes:
- Update docker-compose.prod.yml to use ghcr.io pre-built images instead of local builds
- Fix deployment script to pull latest images rather than building locally
- Add proper GitHub Container Registry authentication
- Remove --build flag that was causing deployment to use stale local code

This should resolve the issue where www.vhtv-stiftung.de wasn't showing the new Verpachtung features.

.github/workflows/ci-cd.yml

@@ -185,11 +185,13 @@ jobs:
       uses: appleboy/ssh-action@v1.0.3
       env:
         DEPLOY_TOKEN: ${{ secrets.DEPLOY_TOKEN }}
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        GITHUB_ACTOR: ${{ github.actor }}
       with:
         host: ${{ secrets.PROD_HOST }}
         username: ${{ secrets.PROD_USERNAME }}
         key: ${{ secrets.PROD_SSH_KEY }}
-        envs: DEPLOY_TOKEN
+        envs: DEPLOY_TOKEN,GITHUB_TOKEN,GITHUB_ACTOR
         script: |
           cd /opt/stiftung
           
@@ -199,11 +201,17 @@ jobs:
           # Copy production docker compose file
           cp deploy-production/docker-compose.prod.yml docker-compose.yml
           
+          # Login to GitHub Container Registry
+          echo $GITHUB_TOKEN | docker login ghcr.io -u $GITHUB_ACTOR --password-stdin
+          
+          # Pull latest images
+          docker-compose pull
+          
           # Stop containers
           docker-compose down
           
-          # Start containers with rebuild
-          docker-compose up -d --build
+          # Start containers with latest images
+          docker-compose up -d
           
           # Wait for containers to be ready
           echo "Waiting for containers to start..."