Remove UA_868 as obsolete (#10994)

Decree of the Cabinet of Ministers of Ukraine dated February 25, 2026,*
No. 262, on amendments to Section 2 of the Plan for the Allocation and
Use of the Radio Frequency Spectrum in Ukraine, has harmonised
Ukrainian regulations on the 868 MHz spectrum with the EU's, thereby
making UA_868 legally obsolete.

* https://zakon.rada.gov.ua/laws/show/262-2026-п

Co-authored-by: Tom <116762865+NomDeTom@users.noreply.github.com>

src/mesh/NodeDB.cpp

@@ -478,6 +478,12 @@ NodeDB::NodeDB()
     LOG_DEBUG("Number of Device Reboots: %d", myNodeInfo.reboot_count);
 #endif
 
+    // UA_868 is obsolete; migrate to EU_868 before resetRadioConfig() below validates the region.
+    if (config.lora.region == meshtastic_Config_LoRaConfig_RegionCode_UA_868) {
+        LOG_INFO("UA_868 region is obsolete, migrating saved config to EU_868");
+        config.lora.region = meshtastic_Config_LoRaConfig_RegionCode_EU_868;
+    }
+
     resetRadioConfig(); // If bogus settings got saved, then fix them
     // nodeDB->LOG_DEBUG("region=%d, NODENUM=0x%x, dbsize=%d", config.lora.region, myNodeInfo.my_node_num, numMeshNodes);