[WIP] Add bundle size exception request flow

[igor10k]

Why?

Remote-DOM UI extension bundles (API version 2025-10 or later) are limited to 64 KB (compressed), enforced at deploy time. Some apps can't reduce their bundles below the limit even after optimization, and Shopify can grant a per-app bundle size exception.

Today there's no way to request one from the CLI, and the deploy error doesn't tell developers what to do next. This PR adds that flow.

What?

Three commits, reviewable independently:

1. Keep esbuild metafiles in the app deploy archive

• Production builds already emit *.metafile.json next to each extension bundle; stop excluding them from the deploy archive so bundle composition can be analyzed when an exception request is reviewed. Sourcemaps remain excluded.
• Note: affects the archive contents for every deploy, not just apps requesting exceptions.

2. Add hidden shopify app bundle-size-exception request command

• Builds each Remote-DOM UI extension for production in a temporary directory and measures raw + compressed sizes.
• Short-circuits when a request is already pending or when all bundles fit the app's current limit.
• Prompts for a justification and confirmation; --reason makes it non-interactive.
• Submits via the new appBundleSizeExceptionRequest App Management mutation. The CLI sends measurements and a justification, and Shopify reviews every request. Server-side userErrors are surfaced directly.
• DeveloperPlatformClient gains bundleSizeException / bundleSizeExceptionRequest (App Management client only).

3. Point at the request flow from bundle-size deploy errors

• When a deploy fails with a structured {type: bundle_size_limit} entry in the error's on payload, the validation-error output gains a "Bundle size exception" section telling the developer to run the request command. Structured detection only — no message parsing.

Testing

Requires an App Management API that exposes the new appBundleSizeExceptionRequest mutation and app.bundleSizeException field (rolling out server-side), and an app with a UI extension on api_version = "2025-10".

1. Request flow: pnpm shopify app bundle-size-exception request --path <app> (--path is optional)
   • Small bundle → "No exception needed" with measured per-extension sizes.
   • Bloat the extension (e.g. inline a large dependency) → justification prompt → confirmation → success message.
   • Re-run → "already pending review" info, no resubmission.
   • --reason "text" → runs with no prompts.
2. Deploy CTA: with an oversized bundle, run pnpm shopify app deploy → the bundle-size validation error shows the "Bundle size exception" section.
3. Metafiles: covered by unit tests in bundle.test.ts (*.metafile.json kept, *.js.map excluded).