Separate UI and control logic with WebSocket communication

- Create UI client (src/ui_client.py) with MIDI controller integration
- Create control server (src/control_server.py) with lighting logic
- Implement WebSocket protocol between UI and control server
- Add startup script (start_lighting_controller.py) for all components
- Update Pipfile with new scripts for separated architecture
- Add comprehensive documentation (README_SEPARATED.md)
- Fix LED connection stability with heartbeat mechanism
- Fix UI knob display and button highlighting
- Maintain backward compatibility with existing MIDI mappings

Pipfile

@@ -19,5 +19,8 @@ websocket-client = "*"
 python_version = "3.12"
 
 [scripts]
-main = "python main.py"
-dev = 'watchfiles "python src/main.py" src'
+ui = "python src/ui_client.py"
+control = "python src/control_server.py"
+sound = "python src/sound.py"
+dev-ui = 'watchfiles "python src/ui_client.py" src'
+dev-control = 'watchfiles "python src/control_server.py" src'