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/test_ollama_feasibility.py

@@ -7,7 +7,6 @@ Ollama Local LLM Feasibility Test
 import json
 import subprocess
 import time
-import sys
 
 UUID = "384b0ff44aaaa1f1"
 ASR_PATH = f"output/{UUID}/{UUID}.asr.json"