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/hybrid_stamp_search.py

@@ -172,7 +172,7 @@ for idx, (sec, frame) in enumerate(candidate_frames):
                     )
 
                     print(f"  🎯 {sec}s | {term} | {s:.2f} | {bw}x{bh}px")
-        except Exception as e:
+        except Exception:
             pass
 
     if found: