Add Liquid docs bundle command

[charlespwd]

What are you adding in this PR?

Related issue: Shopify/developer-tools-team#783

Adds a stable Liquid docs bundle generator to @shopify/theme-check-docs-updater.

New package API:

import { buildThemeLiquidDocsBundle } from '@shopify/theme-check-docs-updater';

const bundle = await buildThemeLiquidDocsBundle();

New CLI command:

pnpm --dir packages/theme-check-docs-updater theme-docs bundle

The command writes a self-contained JSON bundle to stdout:

{
  "schemaVersion": 1,
  "revision": "40f966fc7793462726d9f8573c8d522f8ab44c54",
  "tags": [],
  "filters": [],
  "objects": [],
  "systemTranslations": {},
  "schemas": []
}

Logs from docs loading go to stderr so stdout can be redirected directly into a JSON artifact.

Why: browser-based hosts need a way to publish Liquid docs updates independently from theme-tools and extension releases. This PR only adds the generator; it does not change browser extension runtime behavior.

What's next? Any followup issues?

Follow-up PR: #1016 teaches the browser extension to fetch a published docs bundle at runtime and fall back to bundled docs if unavailable.

A separate host/CDN publisher can use this command after this package version is released, for example:

pnpm dlx @shopify/theme-check-docs-updater@<version> theme-docs bundle > liquid-docs-bundle.json

Tophatting

• pnpm --dir packages/theme-check-docs-updater type-check
• CI=1 pnpm vitest run packages/theme-check-docs-updater/src/themeLiquidDocsBundle.spec.ts packages/theme-check-docs-updater/src/themeLiquidDocsManager.spec.ts
• pnpm --dir packages/theme-check-docs-updater build
• pnpm --silent --dir packages/theme-check-docs-updater theme-docs bundle | jq '.revision, .schemaVersion'
• pnpm format:check
• git diff --check
• Screenshots are not applicable; this is CLI/package API behavior.

Before you deploy

• I included a minor bump changeset
• My feature is backward compatible