cleanup: remove dead code and duplicate docs

- Remove session-ses_2f27.md (161KB raw session log)
- Remove 49 ROOT_* duplicate files across REFERENCE/
- Remove 14 duplicate files between REFERENCE/ root and history/
- Remove asr_legacy.rs (dead code, replaced by asr.rs)
- Remove src/core/worker/ (duplicate JobWorker)
- Remove src/core/layers/ (empty directory)
- Remove 4 .bak files in src/
- Remove 7 dead private methods in worker/processor.rs
- Remove backup directory from git tracking

scripts/find_kids_pose.py

@@ -6,7 +6,6 @@ Heuristic: Kids have a larger head relative to their body height (approx 1:5 or
 
 import json
 import math
-import sys
 
 # Configuration
 POSE_JSON_PATH = "output/384b0ff44aaaa1f1/384b0ff44aaaa1f1.pose.json"
@@ -161,7 +160,7 @@ def find_kids():
     # Sort by timestamp
     sorted_kids = sorted(unique_kids.values(), key=lambda x: x['timestamp'])
     
-    print(f"\nUnique potential kid detections (timestamps):")
+    print("\nUnique potential kid detections (timestamps):")
     for k in sorted_kids:
         print(f"  -> Timestamp: {k['timestamp']:.2f}s | Ratio: {k['ratio']}")