Add independent Companion Bluetooth stealth flag

Keep stealth separate from custom, saved-random and rotating MAC policies without migrating the development MAC mode. Persist authenticated peer state, guard advertising transitions and recovery, and expose the setting through the CLI and WebConfig.

Add regression and CI checks and record exact XIAO BLE pairing, reconnect, reboot and address-rotation hardware results.

src/helpers/esp32/WebConfigServer.cpp

@@ -1797,6 +1797,7 @@ void WebConfigServer::handleConfigGet(AsyncWebServerRequest* req) {
     radio["name"] = (const char*)node.name;
     radio["bluetooth_name"] = (const char*)node.bluetooth_name;
     radio["bluetooth_mac"] = (const char*)node.bluetooth_mac;
+    radio["bluetooth_stealth"] = node.bluetooth_stealth;
     radio["lat"] = node.lat;
     radio["lon"] = node.lon;
     radio["advert_interval"] = node.advert_interval;