fix: Add tuple unpacking for check_existing_positions return value

Fixed TypeError caused by missing tuple unpacking:
- check_existing_positions() returns (has_position, position_info)
- Was accessing as dict directly → TypeError
- Now properly unpacks: has_position, position_info = check_existing_positions()

Fixed in:
- activate_enhanced_scoring.py
- Notebook cells 15, 27, 84, 89

Error resolved: TypeError: tuple indices must be integers or slices, not str

dynamic_thresholds.json

@@ -1,5 +1,5 @@
 {
-  "timestamp": "2026-01-21T13:24:31.582409",
+  "timestamp": "2026-01-21T13:31:39.173342",
   "session_thresholds": {
     "asian": 60,
     "ny": 60,