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/utils/test_mediapipe.py

@@ -9,7 +9,6 @@ Test modules:
 4. Holistic (Face + Pose + Hands)
 """
 
-import sys
 import cv2
 import numpy as np
 import mediapipe as mp
@@ -81,7 +80,7 @@ def test_face_mesh():
             horizontal_dist = abs(p4.x - p3.x)
             ear_left = vertical_dist / horizontal_dist if horizontal_dist > 0 else 0
             
-            print(f"\nEye Aspect Ratio (EAR):")
+            print("\nEye Aspect Ratio (EAR):")
             print(f"  Left eye EAR: {ear_left:.3f}")
             print(f"  Interpretation: {'wide_open' if ear_left > 0.35 else 'normal' if ear_left > 0.2 else 'closed'}")
             
@@ -95,7 +94,7 @@ def test_face_mesh():
             mouth_width = abs(mouth_right.x - mouth_left.x)
             mar = mouth_height / mouth_width if mouth_width > 0 else 0
             
-            print(f"\nMouth Aspect Ratio (MAR):")
+            print("\nMouth Aspect Ratio (MAR):")
             print(f"  MAR: {mar:.3f}")
             print(f"  Interpretation: {'open' if mar > 0.5 else 'closed' if mar < 0.2 else 'slightly_open'}")
         else:
@@ -179,7 +178,7 @@ def test_pose():
             
             # Check if arm is raised
             if right_wrist.y < right_elbow.y < right_shoulder.y:
-                print(f"  Action: raise_right (arm raised)")
+                print("  Action: raise_right (arm raised)")
             
             # Knee angles
             left_hip = landmarks[23]
@@ -241,7 +240,7 @@ def test_hands():
                     "pinky_tip": 20,
                 }
                 
-                print(f"  Key landmarks:")
+                print("  Key landmarks:")
                 for name, i in key_indices.items():
                     lm = landmarks[i]
                     print(f"    {name} ({i}): x={lm.x:.3f}, y={lm.y:.3f}")