fix: address code review round 2 — 9 issues (2 critical, 3 important, 4 minor)

Critical:
- #2: Add _entry_lock in RiskManager to serialize concurrent entry (balance race)
- #3: Add startTime to get_recent_income + record _entry_time_ms (SYNC PnL fix)

Important:
- #1: Add threading.Lock + _run_api() helper for thread-safe Client access
- #4: Convert reset_daily to async with lock
- #8: Add 24h TTL to exchange_info_cache

Minor:
- #7: Remove duplicate Indicators creation in _open_position (use ATR directly)
- #11: Add input validation for LEVERAGE, MARGIN ratios, ML_THRESHOLD
- #12: Replace hardcoded corr[0]/corr[1] with dict-based dynamic access
- #14: Add fillna(0.0) to LightGBM path for NaN consistency with ONNX

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

CLAUDE.md

@@ -142,3 +142,5 @@ All design documents and implementation plans are stored in `docs/plans/` with t
 | 2026-03-07 | `weekly-report` (plan) | Completed |
 | 2026-03-07 | `code-review-improvements` | Partial (#1,#2,#4,#5,#6,#8 완료) |
 | 2026-03-19 | `critical-bugfixes` (C5,C1,C3,C8) | Completed |
+| 2026-03-21 | `dashboard-code-review-r2` (#14,#19) | Completed |
+| 2026-03-21 | `code-review-fixes-r2` (9 issues) | Completed |