feat: add 5 dashboard features — dark mode, trade history, backtests, model insights, alerts

- Dark mode: class-based theme toggle with localStorage persistence and flash prevention
- Trade History (/trades): paginated table, stats cards, equity curve chart with DB API endpoints
- Backtest Viewer (/backtests): log parser for 35 backtest results, sidebar + detail + comparison tabs
- Model Insights: dashboard card + dialog showing feature importance, regime distribution, training history
- Alert/Signal Log (/alerts): signal stats, filterable table with execution tracking
- API: 8 new endpoints with psycopg2 DB connection pool
- Dark mode sweep across books page, about dialog, and all dashboard components
- Architecture docs rewritten with Mermaid diagrams (23 docs)
- README and FEATURES.md rewritten bilingual (Indonesian + English)
- main_live.py: write model_metrics.json on startup and retrain

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

backtests/38_model_comparison_results/comparison_report.txt

@@ -0,0 +1,24 @@
+MODEL COMPARISON REPORT
+==========================================================================================
+
+V1 (Live): models/xgboost_model.pkl
+  Features: 37
+  Trades: 107
+  Win Rate: 43.9%
+  Net P&L: $19.37
+  Profit Factor: 1.04
+  Sharpe: 0.25
+
+V2 (ML V2): backtests/36_ml_v2_results/model_d.pkl
+  Features: 76
+  Trades: 107
+  Win Rate: 65.4%
+  Net P&L: $408.59
+  Profit Factor: 2.58
+  Sharpe: 5.97
+
+IMPROVEMENTS (V2 vs V1):
+  Win Rate: +21.5%
+  Net P&L: $+389.22
+  Profit Factor: +1.54
+  Sharpe: +5.72