refactor: add BoundModelBase model property type

[jooola]

Helps the type checkers to detect mistakes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.01%. Comparing base (c3cd1c9) to head (9b155ce).
⚠️ Report is 46 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #539   +/-   ##
=======================================
  Coverage   96.01%   96.01%           
=======================================
  Files          64       64           
  Lines        2938     2938           
=======================================
  Hits         2821     2821           
  Misses        117      117           

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