feat(dev-proxy): init package

[hyoban]

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Summary

Follow #35842

Screenshots

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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

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.81%. Comparing base (f3c3534) to head (675e0e8).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #35852      +/-   ##
==========================================
- Coverage   85.81%   85.81%   -0.01%     
==========================================
  Files        4460     4458       -2     
  Lines      209098   208945     -153     
  Branches    39091    39054      -37     
==========================================
- Hits       179445   179308     -137     
+ Misses      26482    26466      -16     
  Partials     3171     3171              

Flag	Coverage Δ
dify-ui	93.27% <ø> (ø)
web	86.77% <ø> (-0.01%)	⬇️

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