feat: AI Copilot suggestion chips + typeahead dropdown

- Suggestion chips bar: context-aware (amber for rearrange, indigo for creation)
- Typeahead dropdown: keyword matching on ≥2 chars, Tab to select
- getSelectedMidiItemInfo helper for context detection
- Backend: 4 rearrange presets in ai_presets.py
- PromptTemplateManager: getContextualSuggestions(hasSelectedItem)

tests/test_ai_presets.py

@@ -22,11 +22,13 @@ def test_list_presets_defaults():
     assert res.status_code == 200
     data = res.json()
     assert data["success"] is True
-    assert len(data["presets"]) == 3
+    assert len(data["presets"]) == 7
     names = [p["name"] for p in data["presets"]]
     assert "Epic Orchestra Intro (8 Bars)" in names
     assert "Pop Piano Chords (4 Bars)" in names
     assert "Cyberpunk Synthwave (8 Bars)" in names
+    assert "Jazz Swing Variation" in names
+    assert "80s Synthwave Arpeggiator" in names
 
 
 def test_create_user_preset():
@@ -54,7 +56,7 @@ def test_create_user_preset():
     assert res2.status_code == 200
     names = [p["name"] for p in res2.json()["presets"]]
     assert "My Beat (4 Bars)" in names
-    assert len(res2.json()["presets"]) == 4  # 3 defaults + 1 user
+    assert len(res2.json()["presets"]) == 8  # 7 defaults + 1 user
 
 
 def test_update_user_preset():