perf(app): defer workbench Files surface

[Itsnotaka]

What changed

• load the Files explorer and read-only viewer only after a Files/file workbench tab exists
• keep route reconciliation, tab state, sizing, header, rail, and every other workbench surface eager
• show an exact split-pane loading frame with the final explorer bounds, toolbar height, separator, directory label, and editor geometry
• extend the startup graph gate to keep both Files modules deferred

Why

Workbench tabs are not persisted across process launches, but the 45.2 KiB Files explorer/viewer implementation was statically imported on every Electron start. It owns no startup controller responsibility.

Deep links still mount the Files surface immediately and see the final pixel geometry while the local chunk loads. Once loaded, existing visited-tab mounting and resource caching behavior are unchanged.

Performance

• eager app source: 1,471.1 KiB → 1,430.7 KiB (-2.75%)
• Electron window creation → ready-to-show median: 6,735 ms → 6,445 ms (-4.31%, three clean development starts)
• process-wide Electron median: 7,792 ms → 7,307 ms (-6.22%)
• production initial JS: 2,980,917 B → 2,965,273 B raw (-0.52%); 901,658 B → 898,241 B gzip (-0.38%)

One Vite dependency-optimizer error run was discarded and replaced. No release benchmark loop or UI automation was used.

Validation

• pnpm --filter @honk/app dev:startup-review (0/2 Files modules eager; Vite started)
• pnpm --filter @honk/app build
• 29 focused Files/viewer/workbench route, tab, and presentation tests
• focused Oxfmt and Oxlint
• React Doctor adds no finding for this PR; it reports five warnings in the already-merged shell overlay host

Repository-wide checks retain main's existing failures: onboarding-layout.tsx references missing gearColossus, five files exceed the architecture limit, and v2.tsx has design-lint findings. This PR adds no findings to those checks.

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
honk-marketing	Ready	Preview	Aug 4, 2026 5:32pm

[cursor]

Bugbot is not enabled for your account, so this pull request was not reviewed.

Enable Bugbot in the Cursor dashboard to get automatic reviews on future PRs.