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/simple_face_stats.py

@@ -93,14 +93,14 @@ def main():
         # 直接回答問題
         print("📝 問題回答:")
         print("-" * 40)
-        print(f"Q: 這兩個影片內有幾個人?")
+        print("Q: 這兩個影片內有幾個人?")
         print(f"A: 總共檢測到 {total_faces} 個人臉")
         print()
-        print(f"Q: 幾男幾女?")
+        print("Q: 幾男幾女?")
         print(f"A: 男性 {male_count} 人 ({male_count / total_faces * 100:.1f}%)")
         print(f"   女性 {female_count} 人 ({female_count / total_faces * 100:.1f}%)")
         print()
-        print(f"Q: 平均年齡?")
+        print("Q: 平均年齡?")
         print(f"A: 平均 {avg_age} 歲 (範圍: {min_age}-{max_age}歲)")
         print()
         print("=" * 60)