ci: auto release on main merges

[cafitac]

Summary

• Add an auto-release workflow that runs on pushes to main, bumps the patch version, commits release metadata with [skip release], tags the new version, and pushes the tag to trigger the existing publish workflow.
• Add a reusable scripts/bump_release_version.py helper for synchronized Python/npm/module/lockfile version bumps.
• Add workflow/script regression tests and make release metadata tests future-version-safe.

Release behavior

After this lands, each normal merge to main will:

1. run auto-release,
2. bump MAJOR.MINOR.PATCH to the next patch,
3. push chore: release vX.Y.Z [skip release] back to main,
4. create/push vX.Y.Z,
5. let the existing tag-driven publish.yml publish PyPI/npm and create the GitHub Release.

The [skip release] marker prevents the release commit itself from recursively creating another release.

Verification

• RED observed before implementation:
  • tests/test_release_workflows.py failed because .github/workflows/auto-release.yml did not exist.
  • tests/test_bump_release_version.py failed because scripts/bump_release_version.py did not exist.
• TMPDIR=/Users/reddit/Project/agent-memory/.tmp-test uv run pytest tests/test_release_workflows.py tests/test_bump_release_version.py tests/test_release_metadata.py -q -> 6 passed
• TMPDIR=/Users/reddit/Project/agent-memory/.tmp-test uv run pytest tests/ -q -> 119 passed
• uv run python scripts/check_release_metadata.py -> version metadata synced at 0.1.9
• uv run python scripts/smoke_release_readiness.py -> passed
• uvx --from build python -m build -> passed
• npm pack --dry-run -> passed

Current v0.1.9 publish check

• GitHub Release: https://github.com/cafitac/agent-memory/releases/tag/v0.1.9
• npm: @cafitac/agent-memory@0.1.9
• PyPI: cafitac-agent-memory==0.1.9
• outside-repo smoke passed for npm exec, npx, and uvx using hermes-hook-config-snippet.