test(gepa): add reflective dataset tests for multi-agent trajectory validation

Adds 2 new tests validating make_reflective_dataset captures complete trajectories:
- test_make_reflective_dataset_single_react: Single ReAct module
- test_make_reflective_dataset_orchestrator_with_workers: Multi-agent system (3 modules)

New helpers:
- simple_feedback: Reusable feedback function (consolidates 5 duplicates)
- assert_reflective_example_has_trajectory: Validates trajectory completeness

Tests validate:
- Complete trajectory capture (all iterations with thoughts/tools/observations)
- No duplicate/missing iterations
- Full path preservation in multi-agent systems
- Each module's trajectory captured separately

Improvements:
- Clean up docstrings and remove redundant comments
- Fix whitespace linter warnings (9 auto-fixed)
- Reduce from 1054 to 975 lines

All 8 tests passing (6 detection/reconstruction + 2 new reflective dataset)

Author: Ju-usc