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

tests/integration_test.rs

@@ -175,13 +175,22 @@ fn test_monitor_job_full_roundtrip() {
         error_count: 1,
         last_error: Some("Minor warning".to_string()),
         started_at: Some(
-            NaiveDateTime::parse_from_str("2024-01-01 10:00:00", "%Y-%m-%d %H:%M:%S").unwrap(),
+            chrono::DateTime::parse_from_rfc3339("2024-01-01T10:00:00Z")
+                .unwrap()
+                .into(),
         ),
         updated_at: Some(
-            NaiveDateTime::parse_from_str("2024-01-01 10:30:00", "%Y-%m-%d %H:%M:%S").unwrap(),
+            chrono::DateTime::parse_from_rfc3339("2024-01-01T10:30:00Z")
+                .unwrap()
+                .into(),
         ),
-        created_at: NaiveDateTime::parse_from_str("2024-01-01 09:55:00", "%Y-%m-%d %H:%M:%S")
-            .unwrap(),
+        created_at: chrono::DateTime::parse_from_rfc3339("2024-01-01T09:55:00Z")
+            .unwrap()
+            .into(),
+        processors: vec![],
+        completed_processors: vec![],
+        failed_processors: vec![],
+        video_id: None,
     };
 
     let json = serde_json::to_string(&original).unwrap();