ci(grammars): merge the grammar repin automatically

[maxgfr]

The grammar repin job opened a pull request and stopped there, so every daily run only refreshed a branch nobody merged (#20, open since Sept 11 with green checks). The re-pinned wasm never reached main and never got released — which defeats the point of the job.

What changed

.github/workflows/grammars-repin.yml

• Added a Node 18 smoke gate mirroring ci.yml's smoke-node18 job (loads scripts/engine.mjs, runs the CLI on the mini-repo fixture). A grammar bump also moves web-tree-sitter's inlined runtime, so this is exactly the regression that must not auto-merge unnoticed. The job now runs every check ci.yml would run on that PR — typecheck, test, reproducible bundle, Node 18 smoke — against the exact committed tree.
• The job then squash-merges its own pull request and deletes the remote branch. The PR stays as the record of what landed; it is no longer a review gate nobody attends. Squash keeps main at one conventional fix(grammars): ... subject, which is what semantic-release turns into the patch release. Falls back to a merge commit if squashing is disabled on the repo.
• Branch deletion is an explicit git push origin --delete rather than gh pr merge --delete-branch, since that flag also prunes the local branch the job has checked out; a failed cleanup must not fail a merge that already landed.
• Dropped the gh workflow run ci.yml dispatch — the PR is merged in the same run, so a CI run against a deleted branch had nothing left to guard.

.github/workflows/release.yml

• Added a workflow_dispatch trigger. The merge above is performed with GITHUB_TOKEN, so GitHub's anti-recursion rule (already documented in this file for the image publish) keeps the resulting push to main from starting on: push. The repin job dispatches the release run after merging, so the re-pinned grammars are published instead of sitting on main under a stale ENGINE_VERSION. semantic-release is a no-op when nothing releasable landed, so an extra dispatch is harmless.

Notes

• Self-merging is safe here because every gate runs on the exact bytes being merged, in the job, before the merge — waiting for ci.yml on the branch would only re-run the same checks, and a GITHUB_TOKEN-created PR does not start them by itself.
• Existing PR fix(grammars): bump tree-sitter grammars and re-vendor wasm #20 needs no manual action: the next repin run (daily at 03:41 UTC, or a manual dispatch) re-pushes that branch, refreshes the PR and merges it.
• No behavior change when nothing is out of date — the changed=false path still exits early.

🤖 Generated with Claude Code

https://claude.ai/code/session_012xGuFnYS4EJsb9p7PrMLvQ

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[github-actions]

🎉 This PR is included in version 2.30.1 🎉

The release is available on:

• v2.30.1
• npm package (@latest dist-tag)
• GitHub release

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