fix(esp32): defer station maintenance while an AP owns WiFi

Starting or restarting MQTT during browser OTA could remove the active AP by forcing STA mode. Defer shared MQTT startup and recovery, and Companion WiFi startup, pending credential reloads and saved-SSID retries, until the live SDK AP releases the driver. Preserve the setup owner's deliberate credential handoff and cooperative stop acknowledgement.

Validated 91 source host tests, including 20 new AP ownership cases and nine reverted controls under ASan/UBSan. Hardware and firmware build qualification remain separate; the Arduino mode snapshot is not atomic.

.github/workflows/run-unit-tests.yml

@@ -485,6 +485,8 @@ jobs:
           python3 -B test/test_webconfig_secret_masking.py
           python3 -B test/test_webconfig_station_ownership.py -v
           python3 -B test/test_mqtt_canonical_wifi.py -v
+          python3 -B test/test_mqtt_ap_ownership.py -v
+          python3 -B test/test_companion_ap_ownership.py -v
           python3 -B test/test_heltec_v4_wifi_setup_page.py -v
           python3 -B test/test_sensor_webconfig_capabilities.py -v
           python3 -B test/test_webconfig_ui_runtime.py