add light/dark theme with global persistence

- AppTheme.pas: новый файл, TAppTheme record + DarkTheme()/LightTheme()
- FlatSlider: цвета через SetThemeColors вместо хардкода
- SpectrumView: все цвета из TAppTheme (SetTheme)
- SettingsForm: ApplyTheme(T) с рекурсивным обходом контролов
- DeviceForm: SetTheme(T) — перекраска всех элементов включая TEdit
- Settings: SaveTheme/LoadTheme в корневой секции preferences (не привязано к устройству)
- MainForm: тема загружается при старте, сохраняется при изменении

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

SettingsForm.pas

@@ -27,7 +27,7 @@ uses
   Classes, SysUtils, Math,
   Forms, Controls, Graphics, Dialogs,
   StdCtrls, ExtCtrls, Spin,
-  FlatButton, AudioOutput, AudioInput;
+  FlatButton, AudioOutput, AudioInput, AppTheme;
 
 type
   // PA: MaxPower в Вт, BandCal[0..10] — калибровка 38.8..100.0 на диапазон
@@ -43,6 +43,7 @@ type
   TOnAudioInDevChange = procedure(DevIndex: Integer; const DevName: string) of object;
   TOnVisibilityChange = procedure(ShowSpectrum, ShowWaterfall: Boolean) of object;
   TOnFPSChange = procedure(FPS: Integer) of object;
+  TOnThemeChange = procedure(LightTheme: Boolean) of object;
   TOnCATChange = procedure(
     const SerEnabled: array of Boolean;
     const SerPort: array of string;
@@ -101,6 +102,7 @@ type
     FChkShowSpectrum:    TCheckBox;
     FChkShowWaterfall:   TCheckBox;
     FCmbFPS:             TComboBox;
+    FChkLightTheme:      TCheckBox;
 
     // ---- PA Settings tab controls ----
     FEdMaxPower:     TSpinEdit;
@@ -129,6 +131,7 @@ type
     FOnAudioInDevChange: TOnAudioInDevChange;
     FOnVisibilityChange: TOnVisibilityChange;
     FOnFPSChange:        TOnFPSChange;
+    FOnThemeChange:      TOnThemeChange;
 
     FLoading: Boolean;
 
@@ -138,7 +141,7 @@ type
     procedure BuildRX1Tab;
     procedure BuildPATab;
     procedure BuildCATTab;
-    procedure ApplyTheme;
+    procedure ApplyTheme(const T: TAppTheme);
     procedure NavClick(Sender: TObject);
     procedure SelectPage(APage: TWinControl; ANav: TFlatButton);
 
@@ -167,6 +170,7 @@ type
     procedure OnTXDevChange(Sender: TObject);
     procedure OnVisibilityChkChange(Sender: TObject);
     procedure OnFPSCmbChange(Sender: TObject);
+    procedure OnLightThemeChkChange(Sender: TObject);
     procedure OnMaxPowerChange(Sender: TObject);
     procedure OnBandCalChange(Sender: TObject);
     procedure OnCATSerialChange(Sender: TObject);
@@ -203,6 +207,7 @@ type
     procedure RefreshAudioDevices(AudioOut: TAudioOutput; AudioIn: TAudioInput);
     procedure LoadVisibility(ShowSpectrum, ShowWaterfall: Boolean);
     procedure LoadFPS(FPS: Integer);
+    procedure LoadLightTheme(ALight: Boolean);
     procedure LoadPASettings(MaxPower: Double; const BandCal: array of Double);
     procedure LoadCATSettings(
       const SerEnabled: array of Boolean;
@@ -219,6 +224,7 @@ type
     property OnAudioInDevChange: TOnAudioInDevChange     read FOnAudioInDevChange write FOnAudioInDevChange;
     property OnVisibilityChange: TOnVisibilityChange     read FOnVisibilityChange write FOnVisibilityChange;
     property OnFPSChange:        TOnFPSChange            read FOnFPSChange       write FOnFPSChange;
+    property OnThemeChange:      TOnThemeChange          read FOnThemeChange     write FOnThemeChange;
   end;
 
 implementation
@@ -287,7 +293,7 @@ begin
   FLoading     := False;
   FRXDevCount  := 0;
   BuildUI;
-  ApplyTheme;
+  ApplyTheme(DarkTheme);
 end;
 
 // ---------------------------------------------------------------------------
@@ -611,6 +617,18 @@ begin
   for i := 0 to High(FPS_NAMES) do
     FCmbFPS.Items.Add(FPS_NAMES[i]);
   FCmbFPS.ItemIndex := 8;
+
+  Grp := MakeGroupPanel(FPageDisplay, 'Appearance', MARGIN, 292, 650, 68);
+
+  FChkLightTheme := TCheckBox.Create(Self);
+  FChkLightTheme.Parent := Grp;
+  FChkLightTheme.Caption := 'Light theme';
+  FChkLightTheme.SetBounds(PAD, R1, CHKW, 22);
+  FChkLightTheme.Checked := False;
+  FChkLightTheme.Font.Color := CLR_TEXT;
+  FChkLightTheme.Font.Name := UI_FONT;
+  FChkLightTheme.Font.Size := 9;
+  FChkLightTheme.OnChange := OnLightThemeChkChange;
 end;
 
 // ---------------------------------------------------------------------------
@@ -888,18 +906,66 @@ begin
   end;
 end;
 
-procedure TSettingsForm.ApplyTheme;
+procedure TSettingsForm.ApplyTheme(const T: TAppTheme);
+
+  procedure StyleBtn(B: TFlatButton);
+  begin
+    B.ClrNorm    := T.Panel;
+    B.ClrBorder  := T.Panel;
+    B.ClrHot     := T.BG;
+    B.ClrActive  := T.Panel;
+    B.ClrText    := T.Text;
+    B.ClrTextAct := T.FreqActive;
+    B.Invalidate;
+  end;
+
+  procedure WalkControls(C: TWinControl);
+  var i: Integer; Ctrl: TControl;
+  begin
+    for i := 0 to C.ControlCount - 1 do
+    begin
+      Ctrl := C.Controls[i];
+      if Ctrl is TFlatButton then
+        StyleBtn(TFlatButton(Ctrl))
+      else if Ctrl is TScrollBox then
+      begin
+        TScrollBox(Ctrl).Color := T.BG;
+        WalkControls(TScrollBox(Ctrl));
+      end
+      else if Ctrl is TPanel then
+      begin
+        if TPanel(Ctrl).Height = 1 then
+          TPanel(Ctrl).Color := T.Border
+        else
+          TPanel(Ctrl).Color := T.Panel;
+        WalkControls(TPanel(Ctrl));
+      end
+      else if Ctrl is TLabel then
+      begin
+        if Ctrl.Font.Size >= 12 then
+          TLabel(Ctrl).Font.Color := T.Text
+        else if fsBold in Ctrl.Font.Style then
+          TLabel(Ctrl).Font.Color := T.FreqActive
+        else
+          TLabel(Ctrl).Font.Color := T.TextDim;
+      end
+      else if Ctrl is TCheckBox then
+        TCheckBox(Ctrl).Font.Color := T.Text
+      else if Ctrl is TListBox then
+      begin
+        TListBox(Ctrl).Color      := T.BG;
+        TListBox(Ctrl).Font.Color := T.Text;
+      end
+      else if Ctrl is TWinControl then
+        WalkControls(TWinControl(Ctrl));
+    end;
+  end;
+
 begin
-  Color := CLR_BG;
-  if Assigned(FNavPanel) then FNavPanel.Color := TColor($00151515);
-  if Assigned(FContentPanel) then FContentPanel.Color := CLR_BG;
-  if Assigned(FPageAudio) then FPageAudio.Color := CLR_BG;
-  if Assigned(FPageDisplay) then FPageDisplay.Color := CLR_BG;
-  if Assigned(FPageSpectrum) then FPageSpectrum.Color := CLR_BG;
-  if Assigned(FPageWaterfall) then FPageWaterfall.Color := CLR_BG;
-  if Assigned(FPagePA) then FPagePA.Color := CLR_BG;
-  if Assigned(FPageAdvanced) then FPageAdvanced.Color := CLR_BG;
-  if Assigned(FPageCAT) then FPageCAT.Color := CLR_BG;
+  Color := T.BG;
+  Font.Color := T.Text;
+  WalkControls(Self);
+  Invalidate;
 end;
 
 // ---------------------------------------------------------------------------
@@ -1265,6 +1331,15 @@ begin
   FOnVisibilityChange(FChkShowSpectrum.Checked, FChkShowWaterfall.Checked);
 end;
 
+procedure TSettingsForm.OnLightThemeChkChange(Sender: TObject);
+begin
+  if FLoading then Exit;
+  if FChkLightTheme.Checked then ApplyTheme(LightTheme)
+  else                            ApplyTheme(DarkTheme);
+  if Assigned(FOnThemeChange) then
+    FOnThemeChange(FChkLightTheme.Checked);
+end;
+
 procedure TSettingsForm.OnFPSCmbChange(Sender: TObject);
 var
   Idx: Integer;
@@ -1291,6 +1366,18 @@ begin
   end;
 end;
 
+procedure TSettingsForm.LoadLightTheme(ALight: Boolean);
+begin
+  FLoading := True;
+  try
+    FChkLightTheme.Checked := ALight;
+  finally
+    FLoading := False;
+  end;
+  if ALight then ApplyTheme(LightTheme)
+  else            ApplyTheme(DarkTheme);
+end;
+
 procedure TSettingsForm.LoadPASettings(MaxPower: Double;
   const BandCal: array of Double);
 var i, n: Integer;