WBS-7.3: GAS→Python 마이그레이션 5개 항목 완료 (F14, F02-F06)

- F14: late_chase_risk_score 검증
  * GAS가 유일한 생산처 (Python canonical 없음)
  * migration_action: KEEP_IN_GAS로 정정, status: DONE

- F02/F03/F04/F06: priceBasis 로직 포팅
  * formulas/price_basis_v1.py: select_price_basis_tier2/tier1 구현
  * tests/parity/test_price_basis_parity_v1.py: 8 parity 테스트 (모두 PASS)
  * GAS Number.isFinite() 의미론 정확히 재현 (math.isfinite 사용)
  * 모든 테스트 112/112 PASS

남은 작업 (4개):
- F05: decision_logic (action assignment)
- F07: score_logic (threshold addition)
- F10: routing decision
- F15: late_chase_gate

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

spec/16_data_gaps_roadmap.yaml

@@ -652,6 +652,10 @@ phase_5_platform_transition:
         mock_api_validation: "PASS"
         no_direct_trading_gate: "PASS"
         provenance_completeness_gate: "PASS"
+      notes: >
+        `GatherTradingData.xlsx`는 runtime seed 재생성 fallback으로만 허용한다.
+        collector 본문은 `GatherTradingData.json`만 사용하며, xlsx는 Prepare Raw Seed Snapshot
+        단계에서만 허용된다.
       evidence_artifacts:
         - ".gitea/workflows/kis_data_collection.yml"
         - "Temp/kis_api_credentials_validation_v1.json"