Convert to PlatformIO/Arduino format

- Replace ESP-IDF structure with PlatformIO (platformio.ini)
- Move source files to src/ and include/
- Move libraries to lib/ directory
- Replace FreeRTOS with Arduino task/vTaskDelay
- Use Arduino MIDI library instead of raw TinyUSB
- Dual-core: MIDI on core 0, controller on core 1

sdkconfig.defaults

@@ -1,16 +0,0 @@
-# ESP32-S3 Configuration
-CONFIG_IDF_TARGET="esp32s3"
-
-# USB Configuration
-CONFIG_TINYUSB_DESC_MANUFACTURER_STRING="Ashley Strahle"
-CONFIG_TINYUSB_DESC_PRODUCT_STRING="Loopy Foot Controller"
-CONFIG_TINYUSB_DESC_CDC_STRING="Loopy Foot Controller"
-CONFIG_TINYUSB_MIDI_ENABLED=y
-CONFIG_TINYUSB_MIDI_RX_BUFSIZE=64
-CONFIG_TINYUSB_MIDI_TX_BUFSIZE=64
-
-# FreeRTOS
-CONFIG_FREERTOS_HZ=1000
-
-# Log level
-CONFIG_LOG_DEFAULT_LEVEL_INFO=y