fix(mobile-web): prepare design system before build

[GCWing]

Summary

• Prepare generated design-token and theme package entries before mobile-web dev, type-check, and production builds.
• Treat design-system sources and workspace lockfiles as mobile-web bundle inputs so desktop startup does not reuse stale assets.
• Add regression coverage for lifecycle preparation and incremental rebuild behavior.

Type and Areas

Type: Regression fix

Areas: Mobile web, desktop development tooling, design-system consumption

Motivation / Impact

A clean checkout could fail during desktop:dev because mobile-web resolved @bitfun/theme-bitfun through its generated dist exports before those exports existed. The mobile-web lifecycle now prepares its package dependencies automatically, while preserving the fast no-change startup path.

Verification

• node --test scripts/mobile-web-build.test.mjs — 3 tests passed
• pnpm --dir src/mobile-web run type-check — passed
• pnpm run build:mobile-web — passed; Vite transformed 1421 modules
• node scripts/mobile-web-build.cjs — build succeeded, then a second run correctly skipped as current
• git diff --check origin/1.0.0-explore...HEAD — passed

Reviewer Notes

Only the local Desktop mobile-web resource preparation path was exercised. Browser/E2E and live Remote Workspace, Remote Control, Peer Device Mode, and Detached Dispatch scenarios were not run; no runtime protocol or persisted shape changed.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable (not applicable; no user-facing copy changed).