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/22_atr_adaptive_results/atr_adaptive_20260207_220928.log

@@ -0,0 +1,10 @@
+#22 ATR-Adaptive Exit Results
+Generated: 2026-02-07 22:09:28.783855
+
+  A: baseline_equiv: 738 trades, 77.9% WR, $1,647.94, vs base: $+198.08
+  B: tighter: 748 trades, 78.3% WR, $1,474.95, vs base: $+25.09
+  C: wider: 732 trades, 76.1% WR, $1,845.24, vs base: $+395.38
+  D: tight_be+wide_trail: 743 trades, 79.1% WR, $1,822.86, vs base: $+373.00
+  E: very_tight: 754 trades, 79.0% WR, $1,257.15, vs base: $-192.71
+
+Best: C: wider