feat: sector trend analysis + ETF representative monitor (DAG step_count 81->83)

- src/quant_engine/sector_trend_analysis.py: ETF proxy 기반 11개 섹터 동향 + smart money lens
- src/quant_engine/etf_representative_monitor.py: ETF 대표 종목 8개 추적 + 벤치마크 연동
- tools/build_sector_trend_analysis_v1.py: SECTOR_TREND_ANALYSIS_V1 Temp JSON 생성
- tools/build_etf_representative_monitor_v1.py: ETF_REPRESENTATIVE_MONITOR_V1 Temp JSON 생성
- tools/update_workbook_sector_insights.py: Google Sheets 섹터 인사이트 동기화
- spec/41_release_dag.yaml: step_count 81->83, wave_1에 2개 신규 노드 등록
- validate_engine_harness_gate.py: CHECK_87B (SECTOR_TREND_ANALYSIS_V1) + ETF monitor DAG 스텝 추가
- render_operational_report.py: sector_trend_analysis_v1 / etf_representative_monitor_v1 / portfolio_performance_summary 섹션 추가
- gas_lib.gs: doPost + syncSectorInsightSheets_ (섹터 인사이트 GAS 동기화 엔드포인트)

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

tools/build_etf_representative_monitor_v1.py

@@ -0,0 +1,42 @@
+from __future__ import annotations
+
+import json
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+from src.quant_engine.etf_representative_monitor import build_etf_representative_monitor
+
+
+DEFAULT_JSON = ROOT / "GatherTradingData.json"
+DEFAULT_OUT = ROOT / "Temp" / "etf_representative_monitor_v1.json"
+
+
+def _ensure_utf8_stdio() -> None:
+    if sys.stdout.encoding and sys.stdout.encoding.lower() not in ("utf-8", "utf8"):
+        sys.stdout = open(sys.stdout.fileno(), mode="w", encoding="utf-8", buffering=1)
+    if sys.stderr.encoding and sys.stderr.encoding.lower() not in ("utf-8", "utf8"):
+        sys.stderr = open(sys.stderr.fileno(), mode="w", encoding="utf-8", buffering=1)
+
+
+def main() -> int:
+    _ensure_utf8_stdio()
+    payload = {}
+    if DEFAULT_JSON.exists():
+        try:
+            payload = json.loads(DEFAULT_JSON.read_text(encoding="utf-8"))
+        except Exception:
+            payload = {}
+    result = build_etf_representative_monitor(payload if isinstance(payload, dict) else {})
+    DEFAULT_OUT.parent.mkdir(parents=True, exist_ok=True)
+    DEFAULT_OUT.write_text(json.dumps(result, ensure_ascii=False, indent=2), encoding="utf-8")
+    print("ETF_REPRESENTATIVE_MONITOR_V1")
+    print(json.dumps(result, ensure_ascii=False, indent=2))
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())