feat: add algo order compatibility and orphan order cleanup

- exchange.py: cancel_all_orders() now cancels both standard and algo orders
- exchange.py: get_open_orders() merges standard + algo orders
- exchange.py: cancel_order() falls back to algo cancel on failure
- bot.py: store SL/TP prices for price-based close_reason re-determination
- bot.py: add _cancel_remaining_orders() for orphan SL/TP cleanup
- bot.py: re-classify MANUAL close_reason as SL/TP via price comparison
- bot.py: cancel orphan orders on startup when no position exists
- tests: fix env setup for testnet config and ML filter mocking
- docs: add backtest market context and algo order fix design specs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -149,3 +149,5 @@ All design documents and implementation plans are stored in `docs/plans/` with t
 | 2026-03-21 | `purged-gap-and-ablation` (plan) | Completed |
 | 2026-03-21 | `ml-validation-result` | ML OFF > ML ON 확정, SOL/DOGE/TRX 제외, XRP 단독 운영 |
 | 2026-03-21 | `ml-validation-pipeline` (plan) | Completed |
+| 2026-03-22 | `backtest-market-context` (design) | 설계 완료, 구현 대기 |
+| 2026-03-22 | `testnet-uds-verification` (design) | 설계 완료, 구현 대기 |