replace derive_builder with typed-builder

[goulart-paul]

Replaces the derive_builder crate with typed_builder, keeping external settings building API the same.

The net effect here is to use a lighter crate with fewer subdependencies.

[codecov]

Codecov Report

❌ Patch coverage is 57.89474% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.73%. Comparing base (9af5f21) to head (a33ac7d).

Files with missing lines	Patch %	Lines
src/qdldl/qdldl.rs	50.00%	4 Missing ⚠️
src/solver/implementations/default/settings.rs	63.63%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #209       +/-   ##
===========================================
+ Coverage   79.82%   92.73%   +12.90%     
===========================================
  Files          88       88               
  Lines        7064     7254      +190     
===========================================
+ Hits         5639     6727     +1088     
+ Misses       1425      527      -898     

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