chore: sync StackBlitz to 1.0.0-beta.4 - #44

What changed

• Pin the standalone StackBlitz live lab to the published [email protected].
• Regenerate its frozen pnpm lockfile against the public npm registry.

Why

The release PR intentionally kept the live lab on the immediate predecessor until beta.4 existed on npm. This post-release sync removes that one-version gap.

Impact

The public StackBlitz import now resolves the released beta.4 tarball and provenance-backed integrity hash. No application source, runtime behavior, or public API changed in this PR.

Validation

• pnpm verify:stackblitz
• pnpm check
• Public registry integrity matches the lockfile.
• Privacy scan found no private project names, local usernames, or credential patterns.
• No authored JavaScript files were added or changed.

Relates to #42.