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/controller/CMakeLists.txt

@@ -0,0 +1,3 @@
+idf_component_register(SRCS "app_task.cpp"
+                       INCLUDE_DIRS "."
+                       REQUIRES midi hal)

components/controller/app_task.h

@@ -3,6 +3,7 @@
 
 #include <freertos/FreeRTOS.h>
 #include <freertos/queue.h>
+#include "midi/midi_transport.h"
 #include "hal/led_stub.h"
 #include "hal/switch_stub.h"
 
@@ -17,6 +18,5 @@ struct AppTaskParams {
 BaseType_t app_task(void* parameters);
 
 // Application state management
-void app_process_midi_event(const MidiEvent& event);
+void app_process_midi_event(const MidiEvent& event, LedStub* led_driver);
 void app_process_switch_event(uint8_t switch_id, bool pressed);
-void app_initialize_config();