Fix CAT settings: load before connect, default TCP port 19090

- Settings.pas: add root-level SaveCATSettings/LoadCATSettings so CAT
  config is stored independently of device MAC.
- MainForm.pas FormCreate: initialize CAT defaults, load from saved
  'cat' JSON section, and apply immediately after InitCATEngine — so
  SettingsForm shows correct values before the transceiver connects.
- MainForm.pas OnCATSettingsChange: always save to root 'cat' section
  (not only when device is connected) so changes persist immediately.
- Default TCP CAT port changed from 4992 to 19090 everywhere.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

MainForm.pas

@@ -1018,7 +1018,21 @@ begin
   FWebServer.OnDrive     := WebOnDrive;
   FWebServer.Start;
   FillChar(FCATLastGlobal, SizeOf(FCATLastGlobal), 0);
+  FCATLastGlobal.CATTcpPort := 19090;
+  for i := 0 to 3 do
+  begin
+    FCATLastGlobal.CATSerialBaud[i]     := 9600;
+    FCATLastGlobal.CATSerialDataBits[i] := 8;
+    FCATLastGlobal.CATSerialStopBits[i] := 1;
+    {$IFDEF MSWINDOWS}
+    FCATLastGlobal.CATSerialPort[i] := 'COM' + IntToStr(i + 1);
+    {$ELSE}
+    FCATLastGlobal.CATSerialPort[i] := '/dev/ttyS' + IntToStr(i);
+    {$ENDIF}
+  end;
+  FSettings.LoadCATSettings(FCATLastGlobal);
   InitCATEngine;
+  CATApplySettings(FCATLastGlobal);
   FSMeterPeak    := -130;
   FSMeterMin     := -130;
   FSMeterAvg     := -130;
@@ -4756,10 +4770,10 @@ begin
   FCATLastGlobal.CATTcpEnabled := TcpEnabled;
   FCATLastGlobal.CATTcpPort    := TcpPort;
   CATApplySettings(FCATLastGlobal);
-  if FDevConnected then begin
+  FSettings.SaveCATSettings(FCATLastGlobal);
+  if FDevConnected then
     FSettings.SaveGlobal(FDevMAC, MakeGlobalSettings);
-    FSettings.Save;
-  end;
+  FSettings.Save;
 end;
 
 // --- Getters (called from CAT thread — read only, no sync needed) -----------