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/face_statistics_report.py

@@ -4,7 +4,6 @@
 """
 
 import psycopg2
-import json
 from datetime import datetime
 import sys
 
@@ -235,7 +234,7 @@ def main():
         with open("/tmp/face_statistics_report.txt", "w") as f:
             f.write(report)
 
-        print(f"\n報告已保存到: /tmp/face_statistics_report.txt")
+        print("\n報告已保存到: /tmp/face_statistics_report.txt")
 
     except Exception as e:
         print(f"❌ 生成報告時出錯: {e}")