Phase 5: fill SetBand as a real band-by-index command

SetBand was a skeleton (FCurrentBand := Idx + Changed), leaving BandUp/BandDown
non-functional. Fill it with the band-change logic (XVTR-exit + persist + restore)
that WebAdapter.SyncBand had inline; SyncBand now just calls FController.SetBand.
Gives CAT band up/down/by-index a controller command to call (Phase 4) instead of
routing through the web adapter.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

RadioController.pas

@@ -1545,7 +1545,20 @@ begin
 end;
 
 procedure TRadioController.SetBand(Idx: Integer);
-begin FCurrentBand := Idx; Changed(rfBand); { TODO wiring: RestoreBand } end;
+// Смена HF-диапазона по индексу (web/CAT/BandUp-Down). Выход из XVTR (если активен),
+// персист покидаемого, restore нового. Полная команда — не трогает UI.
+begin
+  if (Idx < 0) or (Idx >= CFG_BAND_COUNT) then Exit;
+  if FCurrentXvtr >= 0 then
+  begin
+    DeactivateXvtr;                // выход в HF (HF-возврат внутри)
+    if Idx = FCurrentBand then Exit;
+  end
+  else if Idx = FCurrentBand then Exit;
+  if FDevConnected then begin SaveCurrentBand; FSettings.Save; end;
+  FCurrentBand := Idx;
+  RestoreBand(Idx);
+end;
 
 procedure TRadioController.BandUp;
 begin if FCurrentBand < CFG_BAND_COUNT - 1 then SetBand(FCurrentBand + 1); end;

WebAdapter.pas

@@ -172,21 +172,7 @@ procedure TWebAdapter.OnBand(Idx: Integer);
 begin FSyncInt := Idx; FController.Invoke(@SyncBand); end;
 
 procedure TWebAdapter.SyncBand;
-// Смена HF-диапазона из web/CAT. Выход из XVTR (если активен) + persist + restore.
+begin FController.SetBand(FSyncInt); end;   // XVTR-выход + persist + restore — в команде
-begin
-  if (FSyncInt < 0) or (FSyncInt >= CFG_BAND_COUNT) then Exit;
-  if FController.FCurrentXvtr >= 0 then
-  begin
-    FController.SetXvtrBand(-1);   // выход в HF (DeactivateXvtr несёт HF-возврат)
-    if FSyncInt = FController.FCurrentBand then Exit;
-  end
-  else if FSyncInt = FController.FCurrentBand then
-    Exit;
-  if FController.FDevConnected then
-  begin FController.SaveCurrentBand; FController.FSettings.Save; end;
-  FController.FCurrentBand := FSyncInt;
-  FController.RestoreBand(FController.FCurrentBand);
-end;
 
 procedure TWebAdapter.OnXvtrBand(Idx: Integer);
 begin FSyncInt := Idx; FController.Invoke(@SyncXvtrBand); end;