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/fast_stamp_search.py

@@ -220,7 +220,7 @@ for sec in range(0, total_sec, FRAME_INTERVAL):
                         print(
                             f"    🎯 {sec}s | {term} | {s:.2f} | {int(orig_w)}x{int(orig_h)}px"
                         )
-            except Exception as e:
+            except Exception:
                 pass
 
     # Save annotated frame if stamps found