Add one-line score visualizer with 3D orb and MP4 export

- Verovio single-system engraving, MuseScore audio/MIDI from the same source
- React + Remotion player with live camera, colour and orb controls
- Express pipeline, render queue and local H.264/AAC export
- MIT license plus third-party notices for the reference skill

.gitignore

@@ -0,0 +1,23 @@
+# Dependencies
+node_modules/
+
+# Build output
+dist/
+*.tsbuildinfo
+
+# Runtime data: uploaded scores, MuseScore exports, rendered MP4s, check frames
+data/
+
+# Logs
+*.log
+
+# Local environment
+.env
+.env.*
+!.env.example
+
+# Editor / OS noise
+.DS_Store
+Thumbs.db
+.idea/
+.vscode/