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/asr_face_stats.py

@@ -96,7 +96,7 @@ def print_stats(dist, total_segments):
     avg_faces = total_faces_sum / total_segments if total_segments > 0 else 0
     max_faces = max(dist.keys()) if dist else 0
 
-    print(f"\n📊 Summary:")
+    print("\n📊 Summary:")
     print(f"   Average faces per segment: {avg_faces:.1f}")
     print(f"   Max faces in a segment:    {max_faces}")
     print(
@@ -110,20 +110,20 @@ def print_stats(dist, total_segments):
     )
 
     # Show some example segments
-    print(f"\n🔍 Example Segments:")
-    print(f"   0 faces:")
+    print("\n🔍 Example Segments:")
+    print("   0 faces:")
     examples = [s for s in segment_details if s["face_count"] == 0][:3]
     for ex in examples:
         print(f"     [{ex['start']:.0f}s-{ex['end']:.0f}s] {ex['text']}...")
 
-    print(f"   1 face:")
+    print("   1 face:")
     examples = [s for s in segment_details if s["face_count"] == 1][:3]
     for ex in examples:
         print(
             f"     [{ex['start']:.0f}s-{ex['end']:.0f}s] {ex['person_ids'][0]}: {ex['text']}..."
         )
 
-    print(f"   3 faces:")
+    print("   3 faces:")
     examples = [s for s in segment_details if s["face_count"] == 3][:3]
     for ex in examples:
         pids = ", ".join(ex["person_ids"])