fix(web): preserve attribution from auth redirect

[CodingOnStar]

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Summary

Screenshots

Before	After
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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 doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've 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

[codecov]

Codecov Report

❌ Patch coverage is 95.65217% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.34%. Comparing base (5741f8f) to head (d93965f).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...b/app/components/external-attribution-recorder.tsx	96.15%	1 Missing ⚠️
web/utils/create-app-tracking.ts	90.90%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #38583      +/-   ##
==========================================
- Coverage   85.34%   85.34%   -0.01%     
==========================================
  Files        5017     5017              
  Lines      266989   267020      +31     
  Branches    50826    50832       +6     
==========================================
+ Hits       227857   227883      +26     
- Misses      34663    34668       +5     
  Partials     4469     4469              

Flag	Coverage Δ
dify-ui	94.61% <ø> (ø)
web	84.84% <95.65%> (-0.01%)	⬇️

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