ci: pass BUILD_ID into Docker build

- Add --build-arg BUILD_ID=${{ github.run_id }} to docker build step
- Ensures index.html placeholder {{BUILD_ID}} is replaced with the actual run ID
- Keeps artifact upload step unchanged

Author: iplaycomputer

.github/workflows/ci-pipeline.yml

@@ -22,12 +22,12 @@ jobs:
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
-
+        
 - name: Build sample image
   run: |
     docker build --build-arg BUILD_ID=${{ github.run_id }} \
-                 -t myorg/sample-app:ci-${{ github.run_id }} \
-                 ./exercises/02-containerize-app/app
+      -t myorg/sample-app:ci-${{ github.run_id }} \
+      ./exercises/02-containerize-app/app
 
 - name: Upload linux artifact
   uses: actions/upload-artifact@v4