Fix dispatch failures and disable automatic cleanup

1. Quote RELEASE_TAG env vars in all workflow files. Unquoted
   ${{ inputs.tag }} caused YAML parse errors on some Gitea runners,
   making dispatch return HTTP 500 for Linux/macOS.

2. Disable automatic release cleanup in both coordinators. The cleanup
   races with async builds -- it deletes the release before builds
   finish uploading their assets. Clean up old releases manually
   from the Gitea UI instead.

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

.gitea/workflows/build-sidecar-macos.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: macos-latest
     env:
       PYTHON_VERSION: "3.11"
-      RELEASE_TAG: ${{ inputs.tag }}
+      RELEASE_TAG: "${{ inputs.tag }}"
     steps:
       - name: Show tag
         run: echo "Building for tag: ${RELEASE_TAG}"