feat: Implement senior audio injection with 5 fallback methods

- Add _cmd_create_arrangement_audio_pattern with 5-method fallback chain
- Method 1: track.insert_arrangement_clip() [Live 12+]
- Method 2: track.create_audio_clip() [Live 11+]
- Method 3: arrangement_clips.add_new_clip() [Live 12+]
- Method 4: Session->duplicate_clip_to_arrangement [Legacy]
- Method 5: Session->Recording [Universal]

- Add _cmd_duplicate_clip_to_arrangement for session-to-arrangement workflow
- Update skills documentation
- Verified: 3 clips created at positions [0, 4, 8] in Arrangement View

Closes: Audio injection in Arrangement View

senior_validation_fixes.txt

@@ -0,0 +1,19 @@
+SENIOR ARCHITECTURE - FIX SUGGESTIONS
+============================================================
+
+Metadata Store:
+
+Fix: If metadata store fails:
+  1. Check database schema in metadata_store.py
+  2. Verify SampleFeatures dataclass definition
+  3. Check for SQL syntax errors in init_database()
+  4. Ensure proper error handling in save/get methods
+
+ArrangementRecorder:
+
+Fix: If ArrangementRecorder fails:
+  1. Check RecordingState enum definition
+  2. Verify RecordingConfig dataclass
+  3. Ensure proper mock objects for testing
+  4. Check state transition logic
+