Make socket operators match Python on integers

[BradyAJohnston]

Adds tests/test_operator_evaluation.py, which evaluates each operator in a tree (via databpy, now a dev dependency) and compares it with Python on the same values. It found:

• Integer &, |, ^, ~ built Boolean Math, casting to booleans (i | 4 raised). They now build Bit Math.
• Integer % was truncated modulo (-7 % 3 == -1). Now floored, like Python and float %. Breaking.
• Integer / truncated (7 / 3 == 2). Now a float Math divide returning a FloatSocket; // stays integer division. Breaking.
• int_socket < float_socket compared the operands the wrong way round after type promotion.

Codegen lifts follow: Bit Math to &/|/^/~, floored modulo to %, and the guards keep Boolean Math fed by integers (and the reverse) as calls.

[codecov]

Codecov Report

❌ Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 98.34%. Comparing base (7a5e9dc) to head (15064c2).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/nodebpy/export/codegen.py	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #245      +/-   ##
==========================================
- Coverage   98.34%   98.34%   -0.01%     
==========================================
  Files         101      101              
  Lines       30286    30307      +21     
==========================================
+ Hits        29786    29806      +20     
- Misses        500      501       +1     

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