feat: 리밸런싱 엔진 V1 + GAS 버그 수정 (2026-06-13)

주요 변경:
- tools/build_rebalance_engine_v1.py: REBALANCE_ENGINE_V1 신규
  * account_snapshot 직접 합산(_build_snap_position_map) → 소수주 분리 행 병합
  * 레짐 소스 macro.REGIME_PRELIM 최우선 (GAS 와 동일)
- src/gas_adapter_parts/gdf_06_rebalance.gs: runRebalanceSheet_() 신규
  * Logger.log / getSpreadsheet_() 로 run_all 연동 수정
- src/gas_adapter_parts/gdc_01_fetch_fundamentals.gs
  * _mergePositionRecord_(): 소수주 중복 행 합산 신규
  * parseInt → parseFloat (qty, availQty)
- src/gas_adapter_parts/gdf_01_price_metrics.gs
  * 미보유 종목 SELL_READY → WATCH_EXIT_SIGNAL
- spec/41_release_dag.yaml: build_rebalance_sheet 노드 추가 (step_count 63)
- spec/51_formula_lifecycle_registry.yaml: REBALANCE_ENGINE_V1 등록

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

spec/43_quant_factor_taxonomy.yaml

@@ -0,0 +1,30 @@
+schema_version: quant_factor_taxonomy.v1
+purpose: Classify factors by horizon, decay, and conflict policy.
+factor_horizons:
+  - scalping
+  - short
+  - mid
+  - long
+required_lifecycle_fields:
+  - factor_id
+  - hypothesis
+  - market_regime_applicability
+  - horizon
+  - decay_half_life
+  - input_fields
+  - formula_id
+  - data_quality_requirements
+  - expected_edge_formula
+  - conflict_precedence
+  - position_sizing_impact
+  - exit_impact
+  - golden_cases
+  - shadow_start_date
+  - activation_threshold
+  - retirement_condition
+  - owner
+factor_retirement_policy:
+  no_edge_improvement_lookback_days: 90
+  shadow_only_before_activation: true
+  retire_when_no_edge_or_high_conflict: true
+conflict_policy: gate_precedence