Region setting (WiFi country, locale, keyboard) on the Super+W screen and Web UI

kiosk-wifi-helper gains region-status/region-set. The country is persisted as
a cfg80211 regdom module option and in the WiFi netplan file; locale and
keyboard go through localectl, validated against what's installed.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A97KUggSE3rBL8veDM5Mr4

kiosk-app/main.js

@@ -1328,6 +1328,13 @@ ipcMain.handle('wifi-request',async(event,req)=>{
   }
   if(!wifiUnlocked)return{ok:false,error:'Enter the PIN first'};
   if(action==='status'||action==='scan')return runWifiHelper(action);
+  if(action==='region-status')return runWifiHelper('region-status');
+  if(action==='region-set'){
+    const input={};
+    for(const k of['country','locale','keyboard'])if(req[k])input[k]=String(req[k]);
+    console.log('[WIFI] Region set:',JSON.stringify(input));
+    return runWifiHelper('region-set',input);
+  }
   if(action==='connect'){
     console.log('[WIFI] Connecting to',JSON.stringify(String(req.ssid||'')));
     const result=await runWifiHelper('connect',{ssid:String(req.ssid||''),password:String(req.password||'')});