Fix web OTA upload and isolate OTA sessions across firmware and goTool.

Split ESP-NOW into core/master/slave modules, block non-OTA UART traffic during updates, and hold the host serial port exclusively so dashboard polling cannot interleave with firmware uploads.

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

main/esp_now_core.h

@@ -0,0 +1,32 @@
+#ifndef ESP_NOW_CORE_H
+#define ESP_NOW_CORE_H
+
+#include "app_config.h"
+#include "esp_err.h"
+#include "esp_now_messages.pb.h"
+#include <stdbool.h>
+#include <stdint.h>
+
+void esp_now_core_store_config(const app_config_t *config);
+const app_config_t *esp_now_core_get_config(void);
+bool esp_now_core_is_master(void);
+uint8_t esp_now_core_network(void);
+uint8_t esp_now_core_wifi_channel(void);
+const uint8_t *esp_now_core_own_mac(void);
+
+uint32_t esp_now_core_now_ms(void);
+bool esp_now_core_mac_equal(const uint8_t *a, const uint8_t *b);
+void esp_now_core_mac_to_str(const uint8_t *mac, char *out, size_t out_len);
+
+esp_err_t esp_now_core_ensure_peer(const uint8_t *mac);
+esp_err_t esp_now_core_ensure_broadcast_peer(void);
+
+esp_err_t esp_now_core_send(const uint8_t *dest_mac,
+                            const alox_EspNowMessage *msg);
+esp_err_t esp_now_core_send_wait(const uint8_t *dest_mac,
+                                 const alox_EspNowMessage *msg);
+
+esp_err_t esp_now_core_init_radio(uint8_t channel);
+void esp_now_core_init_send_done(void);
+
+#endif