Fix Phase 1 skeleton: add build system, fix compilation errors

- Add CMakeLists.txt for project and all components
- Add idf_component.yml with TinyUSB dependency
- Create switch_stub.cpp implementation
- Fix app_task.h to match .cpp implementation (2-param signature)
- Fix led_stub.h/cpp class naming (DefaultLedStub)
- Fix midi_transport.cpp TinyUSB API usage (tud_midi_*)
- Move main.cpp to main/ directory
- Add sdkconfig.defaults for ESP32-S3

components/midi/midi_transport.h

@@ -1,4 +1,4 @@
-// midi/midi_transport.h
+// components/midi/midi_transport.h
 #pragma once
 
 #include <cstdint>
@@ -40,7 +40,10 @@ public:
 private:
     QueueHandle_t event_queue;
     bool initialized;
+    
+    // MIDI packet parsing
+    void parse_midi_packet(const uint8_t* buffer, uint32_t size, MidiEvent& event);
 };
 
-// Forward declaration for USB callback
-void usb_midi_callback(const uint8_t* event, uint32_t size);
+// Task function for USB MIDI processing
+void usb_midi_task(void* pvParameters);