perf(web): improve vinext home startup time

[hyoban]

Important

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2. Ensure there is an associated issue and you have been assigned to it
3. Use the correct syntax to link this PR: Fixes #<issue number>.

Summary

• Lazy-load locale resource modules through per-locale entry files so vinext does not eagerly include every i18n JSON namespace on the first request.
• Move common layout global mounts behind a client-only dynamic mount.
• Lazy-load detail navigation panels that are not needed on the home route.

No linked issue; this came from local vinext dev startup performance investigation.

Rollback measurements for the retained changes:

Optimization	Revert impact
Lazy-load detail navigation panels	14.4s -> 22.8s, +8.4s
Lazy-load common layout mounts	11.5s -> 14.4s, +2.9s
Lazy-load i18n locale resources	22.4s -> 23.7s, +1.3s

Screenshots

Before	After
N/A	N/A

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This does not apply to typos!)
• I have added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I have updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

Validation:

• pnpm --filter dify-web type-check
• pnpm exec vp staged (no staged files)
• pnpm -C web exec vp staged was attempted, but this checkout reports no staged config in web/vite.config.ts.

From Codex

[codecov]

Codecov Report

❌ Patch coverage is 71.87500% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.36%. Comparing base (44e85c0) to head (c4dd4a1).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
web/i18n-config/load-resource.ts	38.46%	8 Missing ⚠️
...nts/main-nav/components/snippet-detail-section.tsx	88.88%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #38219   +/-   ##
=======================================
  Coverage   85.36%   85.36%           
=======================================
  Files        4970     4972    +2     
  Lines      258774   258797   +23     
  Branches    49076    49076           
=======================================
+ Hits       220893   220914   +21     
- Misses      33576    33578    +2     
  Partials     4305     4305           

Flag	Coverage Δ
dify-ui	94.93% <ø> (ø)
web	85.05% <71.87%> (+<0.01%)	⬆️

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