fix(types): preserve response inference for Promise.then handlers

[EdamAme-x]

Close: #4765

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.48%. Comparing base (2de30d7) to head (0ebd771).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4767      +/-   ##
==========================================
- Coverage   91.48%   91.48%   -0.01%     
==========================================
  Files         177      177              
  Lines       11556    11551       -5     
  Branches     3357     3354       -3     
==========================================
- Hits        10572    10567       -5     
  Misses        983      983              
  Partials        1        1              

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[EdamAme-x]

The implementation itself works with this, but it will result in a large diff if we try to fix all patterns (app.|any|(handler x |any|))

[valerii15298]

I don't know specifics here but curious if Awaited would have been helpful https://www.typescriptlang.org/docs/handbook/utility-types.html#awaitedtype