feat: Pluto/AD936x SDR backend (discovery, RX, VHF band plan)

Add ADALM-Pluto / AD9361 support as a second hardware backend alongside
openHPSDR, sharing the WDSP DSP pipeline and the existing controller API
(UI stays decoupled from logic).

- RadioBackend.pas: abstract TRadioBackend + TBackendCaps + TRadioDevice
  (Kind/URI/Serial). THPSDRNetwork now derives from it (state via virtual
  getters); TRadioController.FNetwork is the base type.
- IIOBindings.pas: dynamic libiio loader (runs without libiio present).
- PlutoBackend.pas: scan/probe-by-URI, connect, LO/rate/bandwidth/gain
  control, RX streaming thread (int16->24bit BE -> OnDDCIQ), Q conjugated
  to match WDSP IQ convention. Verified on LibreSDR (AD9361) over network.
- Unified discovery: TDiscoverThread scans both backends; network Plutos
  found via direct ProbeURI (no mDNS needed). ConnectDevice dispatches by
  Dev.Kind (EnsureBackend swaps backend, preserving callbacks).
- DeviceStore/DeviceForm: persist Kind/URI/Serial; save Pluto via
  AddSavedPluto so saved/autostart devices reconnect across restarts.
- VHF/UHF band plan (BoardUtils, kind-aware): 6m..ADS-B for Pluto; fixes
  HF clamps (band detect, mouse-wheel 60 MHz cap, freq-display max).
- SampleRateOverlay: configurable presets (Pluto 576k..5760k, >520 ksps),
  auto-width to fit.

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

DeviceForm.pas

@@ -7,7 +7,7 @@ interface
 uses
   Classes, SysUtils, FlatButton, FlatEdit, FlatListBox, AppTheme, Forms, Controls, Graphics, Dialogs,
   StdCtrls, ExtCtrls, ComCtrls,
-  BoardUtils, PlatformUtils, DeviceStore;
+  BoardUtils, PlatformUtils, DeviceStore, RadioBackend;
 
 type
   // Результат диалога
@@ -86,6 +86,9 @@ type
     function  GetAutoStartBoardType: Integer;
     function  GetSavedBoardType(Idx: Integer): Integer;
 
+    // Текст поля ручного ввода IP/URI (для probe сетевых Pluto при discovery).
+    function  ManualIP: string;
+
     // Получить/сбросить результат
     procedure ClearResult;
     // Общее хранилище устройств — назначается владельцем (MainForm/контроллер)
@@ -466,7 +469,12 @@ begin
     Exit;
   end;
   D := FStore.Discovered(Idx);
-  NewIdx := FStore.AddSaved(D.DisplayName, D.IPAddress, D.BoardType);
+  // Pluto сохраняем с Kind/URI/Serial (иначе после перезапуска резолвится как
+  // HPSDR по голому IP и не подключается).
+  if D.Kind = bkPluto then
+    NewIdx := FStore.AddSavedPluto('PlutoSDR', D.URI, D.Serial)
+  else
+    NewIdx := FStore.AddSaved(D.DisplayName, D.IPAddress, D.BoardType);
   RefreshSavedList;
   LstSaved.ItemIndex := NewIdx;
 end;
@@ -518,6 +526,11 @@ begin
   ModalResult := mrCancel;
 end;
 
+function TDeviceDialog.ManualIP: string;
+begin
+  if EdIP <> nil then Result := Trim(EdIP.Text) else Result := '';
+end;
+
 procedure TDeviceDialog.ClearResult;
 begin
   FResult.Accepted  := False;