debug: add AP DNS server for client join probes

firmware/esp32/overland-controller/overland-controller.ino

@@ -1,6 +1,7 @@
 #include <WiFi.h>
 #include <esp_heap_caps.h>
 #include <WebServer.h>
+#include <DNSServer.h>
 #include <Preferences.h>
 #include <esp_wifi.h>
 #include <esp_system.h>
@@ -1459,6 +1460,7 @@ setInterval(load,3000);
 )rawliteral";
 
 WebServer server(80);
+DNSServer dnsServer;
 
 #define API_V1(path) "/api/v1" path
 
@@ -1635,6 +1637,9 @@ void restartAccessPoint() {
     heapCheckpoint("before:startAccessPoint");
     startAccessPoint();
     heapCheckpoint("after:startAccessPoint");
+
+    dnsServer.start(53, "*", WiFi.softAPIP());
+    Serial.println("DNS Server Started");
 }
 
 void sendSimpleJsonError(int status, const char* error, const char* detail) {
@@ -4276,6 +4281,7 @@ void setup() {
 }
 
 void loop() {
+    dnsServer.processNextRequest();
     server.handleClient();
 #if DASHBOARD_UART_ENABLED
     pollDashboardUart();