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/check_code_document_consistency.py

@@ -6,9 +6,7 @@
 核心原則：當設計與實現出現矛盾時，以實際的 Rust 代碼實現為最高權威
 """
 
-import os
 import re
-import sys
 from pathlib import Path
 
 
@@ -177,7 +175,7 @@ def main():
     issues = check_terminology_consistency(implemented_variants)
 
     # 3. 顯示結果
-    print(f"\n📊 檢查完成:")
+    print("\n📊 檢查完成:")
     print(f"  發現問題數: {len(issues)}")
 
     if issues: