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/simple_api_test.py

@@ -34,7 +34,7 @@ def test_endpoint(endpoint, method="GET", data=None):
         print(f"Headers: {dict(response.headers)}")
 
         if response.status_code == 200:
-            print(f"✅ Success!")
+            print("✅ Success!")
             if response.text:
                 print(f"Response (first 500 chars): {response.text[:500]}")
             return True