Add BLE host transport selectable via DIP8 alongside UART.

Master can speak the same framed protobuf protocol over NimBLE or UART; goTool gains -ble, ble-rtt, and ble-stream timing checks for ESP-NOW coexistence.

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

main/host_transport.h

@@ -0,0 +1,36 @@
+#ifndef HOST_TRANSPORT_H
+#define HOST_TRANSPORT_H
+
+#include "esp_err.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/queue.h"
+#include <stddef.h>
+#include <stdint.h>
+
+/** TX callback: send a complete framed packet (0xAA … 0xCC). */
+typedef esp_err_t (*host_tx_fn_t)(const uint8_t *frame, size_t frame_len);
+
+/** Set the active host TX backend (UART write or BLE notify). */
+void host_transport_set_tx(host_tx_fn_t tx_fn);
+
+/** Bind the shared cmd_queue used by uart_enqueue_packet / host RX. */
+void host_transport_set_cmd_queue(QueueHandle_t cmd_queue);
+
+QueueHandle_t host_transport_cmd_queue(void);
+
+/**
+ * Build AA|len|payload|xor|CC and send via the registered TX backend.
+ * Same semantics as uart_send_framed.
+ */
+esp_err_t host_send_framed(const uint8_t *payload, size_t len);
+
+/**
+ * Feed raw host RX bytes into the shared frame parser and enqueue complete
+ * packets onto the cmd_queue.
+ */
+void host_rx_bytes(const uint8_t *data, size_t len);
+
+/** Enqueue a completed uart_packet_t (payload[0]=msg type). */
+bool host_enqueue_packet(const uint8_t *payload, uint8_t len);
+
+#endif