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/23_confidence_weight_results/conf_weight_20260207_220909.log

@@ -0,0 +1,10 @@
+#23 Confidence Weight Rebalance Results
+Generated: 2026-02-07 22:09:09.940414
+
+  A: boost_fvg_ob: 690 trades, 72.0% WR, $1,339.85, filtered: 0, vs base: $-110.01
+  B: fvg_dominant: 690 trades, 72.0% WR, $1,337.55, filtered: 0, vs base: $-112.31
+  C: ob_dominant: 689 trades, 72.3% WR, $1,391.17, filtered: 0, vs base: $-58.69
+  D: require_fvg|ob: 682 trades, 72.9% WR, $1,252.86, filtered: 0, vs base: $-197.00
+  E: min_conf_0.55: 654 trades, 71.1% WR, $1,030.46, filtered: 222, vs base: $-419.40
+
+Best: C: ob_dominant