fix(docker): add index annotations to link GHCR package to repository

Multi-platform builds create a manifest index pointing to per-platform
images. The existing labels parameter only sets labels on per-platform
image configs, but GHCR reads annotations from the manifest index for
repository auto-linking. Add index-level annotations so the package
appears under the repo Packages tab instead of only the user profile.

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

.github/workflows/docker-release.yml

@@ -121,5 +121,8 @@ jobs:
             org.opencontainers.image.source=https://github.com/${{ github.repository }}
             org.opencontainers.image.version=${{ steps.meta.outputs.version }}
             org.opencontainers.image.revision=${{ steps.meta.outputs.revision }}
+          annotations: |
+            index:org.opencontainers.image.source=https://github.com/${{ github.repository }}
+            index:org.opencontainers.image.description=CCS Dashboard container image
           cache-from: type=gha
           cache-to: type=gha,mode=max