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/integrate_face_asrx.py

@@ -7,7 +7,6 @@ Face + ASRX 整合處理器
 import sys
 import json
 import argparse
-import os
 from pathlib import Path
 from datetime import datetime
 
@@ -194,7 +193,7 @@ def integrate_face_asrx(face_path, asrx_path, output_path, time_threshold=1.0):
             f"    With face: {speaker['with_face']} ({speaker['with_face'] / speaker['segment_count'] * 100:.0f}%)"
         )
 
-    print(f"\n[Face-ASRX] Integration complete!")
+    print("\n[Face-ASRX] Integration complete!")
 
 
 def main():