chore: add some typing

[aparcar]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.56%. Comparing base (5e65dec) to head (1fd429b).
Report is 119 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1023      +/-   ##
==========================================
+ Coverage   80.75%   90.56%   +9.80%     
==========================================
  Files          15       14       -1     
  Lines         977     1081     +104     
==========================================
+ Hits          789      979     +190     
+ Misses        188      102      -86     

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[aparcar]

@efahl would you be so kind and help with this typing effort :)?

[efahl]

No problem. I've got a bunch of typing/docstring-ish stuff in BuildRequest that I've been sitting on for months that I'll polish up and submit, and look at the rest of this, too.

[efahl]

@aparcar, do you have mypy or something added to your env to test the typing annotations?