feat: Add Docker build combinations for non-versioning prefixes

- Add support for prefix+docker combinations (docs+docker:, chore+docker:, etc.)
- Enable Docker build for non-versioning changes when requested
- Add repository_dispatch trigger for Docker workflow
- Update Docker tagging for PR-based builds (pr-X, main-sha)
- Update PR template with new prefix options

This allows contributors to force Docker builds for documentation,
maintenance, and other non-versioning changes when needed.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/build_and_publish_docker.yml

@@ -3,6 +3,8 @@ name: Build and Publish Docker Image to GHCR
 on:
   push:
     tags: [ 'v*' ]
+  repository_dispatch:
+    types: [docker-build]
 
 env:
   REGISTRY: ghcr.io
@@ -38,6 +40,8 @@ jobs:
         tags: |
           type=ref,event=tag
           type=raw,value=latest,enable={{is_default_branch}}
+          type=sha,prefix=main-,enable=${{ github.event_name == 'repository_dispatch' }}
+          type=raw,value=pr-${{ github.event.client_payload.pr_number }},enable=${{ github.event_name == 'repository_dispatch' && github.event.client_payload.pr_number != '' }}
 
     - name: Build and push Docker image
       uses: docker/build-push-action@v5