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/language_router.py

@@ -297,10 +297,10 @@ def main():
             print(f"  檔案路徑: {result['file_path']}")
             print(f"  檔案存在: {result['file_exists']}")
             if result.get("fallback_used"):
-                print(f"  使用了回退: 是")
+                print("  使用了回退: 是")
                 print(f"  回退原因: {result.get('fallback_reason', '未知')}")
             else:
-                print(f"  使用了回退: 否")
+                print("  使用了回退: 否")
             print(f"  可用語言: {', '.join(result['available_languages'])}")
         else:
             if result["file_exists"]: