ci: auto-create GitHub release on tag push

[BeadW]

Summary

Adds a release.yml workflow that fires whenever a v* tag is pushed. It creates a GitHub release automatically using --generate-notes to pull in commit messages and PR titles since the previous tag.

New release flow

# bump version in pyproject.toml + plugin.json, merge to main, then:
git tag v0.3.3
git push origin v0.3.3
# → workflow fires, release created automatically

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