Add POST /avm/v2/compare-v1 endpoint that runs both v1 (single-model)
and v2 (ensemble) AVM predictions on the same property and returns a
side-by-side comparison with price diff, confidence delta, and a
recommendation on which model to prefer.
- ABComparisonRequest/Response schemas in avm_v2 models
- compare_v1() method in AVMv2EnsembleService
- 4 new integration tests for the comparison endpoint
- All 47 Python tests pass
Co-Authored-By: Paperclip <noreply@paperclip.ing>