feat: add release workflow using shared workflow

Triggers on push to main and uses the shared Release workflow
from unboundsoftware/shared-workflows.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitea/workflows/release.yaml

@@ -0,0 +1,9 @@
+name: Release
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  release:
+    uses: unboundsoftware/shared-workflows/.gitea/workflows/Release.yml@main