Add command queue dispatcher and VERSION UART handler.

Centralize command dispatch over a FreeRTOS queue so UART and future
ESP-NOW transports can register handlers; implement the protobuf VERSION
command with framed nanopb responses including build git hash.

Co-authored-by: Cursor <cursoragent@cursor.com>

main/uart_proto.c

@@ -0,0 +1,23 @@
+#include "uart_proto.h"
+#include "pb_encode.h"
+#include "uart.h"
+#include <string.h>
+
+esp_err_t uart_send_uart_message(const alox_UartMessage *msg) {
+  uint8_t pb_buf[MAX_PAYLOAD_SIZE];
+  pb_ostream_t stream = pb_ostream_from_buffer(pb_buf, sizeof(pb_buf));
+
+  if (!pb_encode(&stream, alox_UartMessage_fields, msg)) {
+    return ESP_FAIL;
+  }
+
+  uint8_t payload[MAX_PAYLOAD_SIZE];
+  if (stream.bytes_written + 1 > sizeof(payload)) {
+    return ESP_ERR_NO_MEM;
+  }
+
+  payload[0] = (uint8_t)msg->type;
+  memcpy(&payload[1], pb_buf, stream.bytes_written);
+
+  return uart_send_framed(payload, stream.bytes_written + 1);
+}