Fix mDNS network change detection

[schjonhaug]

Summary

• treat mDNS enablement changes as network changes so saving the setting triggers the required reboot
• add a native AmsConfiguration regression suite backed by an in-memory EEPROM stub
• run the new configuration suite in pull-request and main-branch CI

Testing

• pio test -e native_config
• verified red/green: the mDNS assertion fails without the production fix and passes with it
• pio run -e esp8266
• pio run -e esp32s2

[ArnieO]

Awaiting @gskjold assessment.