fix(health): Fix lint issues to improve project health score

Fixed multiple lint issues identified by ruff:
- B007: Renamed unused loop variables to _task_type and _agent
- F401: Removed unused rich.progress imports
- F841: Removed unused mock_stdout variable assignment
- Fixed type hints: Changed dict[str, int] to dict[str, int | float]
  to allow both int and float values in stats dictionaries

These fixes improve code quality and resolve warnings that were
lowering the project health score.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: silversurfer562