Surface an in-app version/build stamp (version + commit) for support

[BorisTyshkevich]

Part of #68 (Roadmap to 1.0.0) — should-have.

Problem

The app version (0.1.4) lives only in package.json — it is not surfaced in the UI or baked into the build (build/build.mjs injects no version). The whole app is one self-contained dist/sql.html copied onto clusters, so when a user reports a bug there's no way to tell which build they're on, or whether a redeploy actually went live.

Ask

• Inject the version + short commit at build time in build/build.mjs (e.g. read package.json version + git rev-parse --short HEAD, replace a template token).
• Surface it in the UI — a small "vX.Y.Z (abcdef)" in the File/user menu or a footer/About.

Acceptance

• dist/sql.html carries the version + commit, shown somewhere in the UI.
• Build still works offline / when not a git checkout (graceful fallback when no commit available).
• Any touched src/ stays at the per-file coverage gate.