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>

package.json

@@ -8,6 +8,7 @@
     "ops:validate": "python tools/run_release_dag_v3.py --mode release",
     "ops:build": "python tools/build_bundle.py",
     "ops:render": "python tools/render_operational_report.py --json GatherTradingData.json --output Temp/operational_report.md --report-json-output Temp/operational_report.json",
+    "ops:sector-workbook": "python tools/update_workbook_sector_insights.py",
     "ops:release": "python tools/run_release_dag_v3.py --mode full",
     "ops:package": "python tools/refresh_trading_calendar.py && python tools/prepare_upload_zip.py --validation-mode release --profile",
     "prepare-upload-zip": "python tools/refresh_trading_calendar.py && python tools/prepare_upload_zip.py",