feat: add multi-repo cloning, remove dynamic/serverless mode

Add githubRepos list field for cloning multiple repositories into a
single dev container with multi-root workspace file generation.
Remove the unused dynamic deployment mode (Knative, routing proxy,
serverless scripts) to simplify the chart to persistent-only.
Fix release workflow cache-to setting that violated the no-cache policy.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/release-unified.yaml

@@ -101,7 +101,6 @@ jobs:
             ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ steps.version.outputs.tag }}
             ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ steps.version.outputs.version }}
             ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
-          cache-to: type=gha,mode=max
           platforms: linux/amd64
 
       - name: Publish Helm Chart to GitHub Pages