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>

docs/adr/ADR-0001-single-source-of-truth.md

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+# ADR-0001 Single Source of Truth
+
+## Context
+
+The engine has multiple JSON versions for the same concept, which creates stale reads and conflicting runtime authority.
+
+## Decision
+
+Use `canonical_manifest.yaml` and the canonical artifact resolver as the runtime authority for each concept.
+
+## Consequence
+
+Runtime readers must use one canonical path per concept. Deprecated files remain archived only.
+
+## Rollback
+
+If a canonical artifact is invalid, rebuild the canonical copy rather than falling back to a deprecated runtime source.
+

docs/adr/ADR-0002-gas-thin-adapter.md

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+# ADR-0002 GAS Thin Adapter
+
+## Context
+
+GAS has accumulated business logic that belongs in Python validation and builders.
+
+## Decision
+
+Constrain GAS to collection, normalization, export, and display responsibilities.
+
+## Consequence
+
+Decision, sizing, stop-loss, take-profit, and risk calculations must live in deterministic Python builders.
+
+## Rollback
+
+If a GAS function becomes a business-logic dependency, move the logic into Python and keep only a thin adapter in GAS.
+

docs/adr/ADR-0003-no-llm-numeric-generation.md

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+# ADR-0003 No LLM Numeric Generation
+
+## Context
+
+LLM-generated prices, quantities, and thresholds caused authority collisions and provenance loss.
+
+## Decision
+
+LLM outputs must be copy-only. All numeric values must come from harness or canonical artifacts.
+
+## Consequence
+
+Prompt and report contracts must render numbers only when a source artifact already provides them.
+
+## Rollback
+
+There is no rollback path that reintroduces free-form numeric generation. That would violate the operating contract.
+

docs/adr/ADR-0004-shadow-before-active.md

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+# ADR-0004 Shadow Before Active
+
+## Context
+
+Replay and shadow artifacts often look complete before live T+20 sample quality is sufficient.
+
+## Decision
+
+Shadow or advisory formulas may be rendered, but only active formulas may drive live execution.
+
+## Consequence
+
+Live sample thresholds remain mandatory before promotion.
+
+## Rollback
+
+If active promotion is found without live qualification, demote the artifact and restore shadow-only status.
+