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

tools/serve.bat

@@ -9,8 +9,9 @@ echo   ESP32 COMM Host Server
 echo   PORT: %PORT%
 echo ========================================
 echo.
-echo   WiFi OTA:   http://localhost:%PORT%/index.html
-echo   BLE  OTA:   http://localhost:%PORT%/ble_ota.html
+echo   OTA Console:   http://localhost:%PORT%/index.html
+echo.
+echo   Switch WiFi / BLE mode in the "Device Connect" card.
 echo.
 echo   Press Ctrl+C to stop
 echo ========================================