Use uv in CI and Add __len__ for PyOperations

[lan496]

Closes #27

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 89.44%. Comparing base (c0a6e4a) to head (f5e9878).

Files with missing lines	Patch %	Lines
moyopy/src/base.rs	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #29      +/-   ##
==========================================
- Coverage   89.50%   89.44%   -0.06%     
==========================================
  Files          32       32              
  Lines        4527     4530       +3     
==========================================
  Hits         4052     4052              
- Misses        475      478       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.