feat(ci): port publish-runtime.yml to .gitea/workflows/ (issue #206)

publish-runtime.yml was dead on Gitea Actions because Gitea reads
.gitea/workflows/, not .github/workflows/ (the GitHub Actions paths are
ignored). Issue #206 identified this as one of three bugs blocking the
runtime versioning pipeline.

Changes:
- Add .gitea/workflows/publish-runtime.yml (canonical Gitea version)
  - Drop environment: + id-token: write (Gitea has no OIDC/OAuth)
  - Replace pypa/gh-action-pypi-publish with twine upload using PYPI_TOKEN secret
  - Replace github.ref_name with ${GITHUB_REF#refs/tags/} (Gitea exposes github.ref)
  - Drop merge_group trigger (Gitea has no merge queue)
  - Drop staging branch trigger (staging branch does not exist)
  - Cascade step unchanged (DISPATCH_TOKEN + Gitea API already compatible)
- Add DEPRECATED notice to .github/workflows/publish-runtime.yml

Required secrets (repo Settings → Actions → Variables and Secrets):
  PYPI_TOKEN: PyPI API token for molecule-ai-workspace-runtime
  DISPATCH_TOKEN: Gitea PAT with write:repo on template repos (already used)

Closes #206 (publish-runtime Gitea port).

.github/workflows/publish-runtime.yml

@@ -1,5 +1,15 @@
 name: publish-runtime
 
+# DEPRECATED on Gitea Actions — this file is kept for reference only.
+# Gitea Actions reads .gitea/workflows/, not .github/workflows/.
+# The canonical version is now: .gitea/workflows/publish-runtime.yml
+# That port:
+#   - Drops OIDC trusted publisher (Gitea has no environments/OIDC)
+#   - Uses PYPI_TOKEN secret instead of gh-action-pypi-publish
+#   - Uses ${GITHUB_REF#refs/tags/} instead of github.ref_name
+#   - Drops staging branch trigger (staging branch does not exist)
+#   - Drops merge_group trigger (Gitea has no merge queue)
+#
 # Publishes molecule-ai-workspace-runtime to PyPI from monorepo workspace/.
 # Monorepo workspace/ is the only source-of-truth for runtime code; this
 # workflow is the bridge from monorepo edits to the PyPI artifact that