Fix supply voltage display: correct constant per board type, hide on unsupported boards

Per Appendix A of openHPSDR Ethernet Protocol v4.3:
- Boards 1,2,3 (Hermes/Angelia): V = ADC/4095 * 3.3 (was always using this)
- Boards 4,5 (Orion/Orion MkII): V = ADC/4095 * 5.0 (was wrong, showing ~66% of real value)
- Board 0 (Atlas) has no supply voltage measurement per protocol spec
  ("not Atlas bus systems")
- Boards 6 (Hermes Lite), 10 (Saturn): constant not documented, hide Supply field

ADCToSupplyVolts now takes BoardType and returns -1.0 for unsupported boards.
DoUpdateStatus omits the Supply field when -1.0 is returned.

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

MainForm.pas

@@ -2291,7 +2291,8 @@ begin
   ExcPwr  := (Status.ExciterPwr0Hi shl 8) or Status.ExciterPwr0Lo;
   FwdPwr  := (Status.FwdPwrAlex0Hi shl 8) or Status.FwdPwrAlex0Lo;
   RevPwr  := (Status.RevPwrAlex0Hi shl 8) or Status.RevPwrAlex0Lo;
-  SupplyV := ADCToSupplyVolts((Status.SupplyVoltsHi shl 8) or Status.SupplyVoltsLo);
+  SupplyV := ADCToSupplyVolts((Status.SupplyVoltsHi shl 8) or Status.SupplyVoltsLo,
+               FNetwork.Device.BoardType);
   // FLastSMeter обновляется только из WDSP (GetSMeterDBm) в SpectrumTimerTick —
   // ExciterPwr это мощность TX, не уровень принятого сигнала.
   FwdW := ADCToWatts100(FwdPwr);
@@ -2319,9 +2320,14 @@ begin
   LblFwdPwr.Caption := Format('%.0fW', [FwdW]);
   LblSWRVal.Caption := Format('SWR:%.1f', [SWRV]);
   if PLLLock then PLLStr := 'PLL OK' else PLLStr := 'PLL?';
-  StatusBar1.Panels[2].Text :=
-    Format('Supply: %.1fV | FWD: %.0fW | SWR: %.1f | %s',
-           [SupplyV, FwdW, SWRV, PLLStr]);
+  if SupplyV >= 0 then
+    StatusBar1.Panels[2].Text :=
+      Format('Supply: %.1fV | FWD: %.0fW | SWR: %.1f | %s',
+             [SupplyV, FwdW, SWRV, PLLStr])
+  else
+    StatusBar1.Panels[2].Text :=
+      Format('FWD: %.0fW | SWR: %.1f | %s',
+             [FwdW, SWRV, PLLStr]);
 
   // Hardware PTT (foot switch / mic PTT) — обнаружение фронта
   if HWPTT <> FHWPTTActive then