After Wave 1-4 (PRs #502/#504/#505/#508/#513/#507/#517), the real estimator
in services/estimator.py is the only path used by /estimate. The legacy
_mock_estimate / _PRICE_BANDS / _gen_analogs helpers + _estimate_legacy_mock
function were kept as a fallback during early development and are now
unreachable.
Removes:
- _EKB_STREETS, _PRICE_BANDS constants
- _floor_factor, _repair_factor, _confidence, _gen_analogs, _mock_estimate
- _estimate_legacy_mock
- unused imports (random, json, timedelta)
Verified: no external references via grep.
PR 8 of 8 — closes Decision_TradeIn_DataQuality_8PR_Roadmap.
