docs(README): 合并WiFi OTA和BLE OTA

- 调整ESP32_COMM/finalize函数执行顺序：先进行SHA-256校验比对，
  再调用esp_ota_end和设置启动分区
- 更新BLE传输收尾描述，明确设备端读回OTA分区进行SHA比对的流程，
  以及FINISH事件的上报机制

main/relay/ota_relay.cpp

@@ -1,4 +1,4 @@
-/*
+/*
  * ota_relay.cpp - OTA 中继核心状态机实现
  * T2.3, T2.4, T3.1 - T3.7
  *
@@ -849,7 +849,7 @@ ota_result_t OtaRelay::sendNonceAndAuthenticate()
     uint32_t mem_addr = (uint32_t)(uintptr_t)m_nonceServer;
     uint32_t rand_seed = 0x12345678;
 
-    Protocol::scrambleGenerate(timestamp, mem_addr, rand_seed, m_nonceServer);
+    Protocol::instance().scrambleGenerate(timestamp, mem_addr, rand_seed, m_nonceServer);
 
     DEBUG_INFO("OTA", "--- 认证步骤 1: 发送 CHALLENGE ---");
     DEBUG_INFO("OTA", "发送 nonce_server (16B), timestamp=0x%08X", timestamp);