feat: unify band plan across desktop + web UIs

Web band selector was hardcoded to the HF plan, so on Pluto it showed
160m..6m instead of the VHF/UHF plan and highlighted the wrong entry
(band switching itself already worked: web sends idx, controller maps it
via the IsPluto plan). Mirror the sample-rate unification.

Single source of truth = BoardUtils -> controller:
- BoardUtils: TBandInfo/TBandPlanArray + BuildBandPlan(Pluto).
- TRadioController.BandPlan returns BuildBandPlan(IsPluto).

Both UIs derive from it:
- Desktop already plan-aware (RelabelBands + RestoreBand) - unchanged.
- Web: WebServer.SetBands + "bands" in state JSON; hosts push
  BandPlan on connect/startup; JS builds the band selector from
  state.bands (BAND_N/BAND_F now dynamic).

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

BoardUtils.pas

@@ -6,6 +6,15 @@ unit BoardUtils;
 
 interface
 
+type
+  // Один диапазон плана (имя кнопки + частота по умолчанию). Общий тип для
+  // desktop/web UI — единый источник band-плана через TRadioController.BandPlan.
+  TBandInfo = record
+    Name:   string;
+    FreqHz: Double;
+  end;
+  TBandPlanArray = array of TBandInfo;
+
 function BoardTypeName(BoardType: Integer): string;
 // Короткое человекочитаемое имя AD936x-платы по hw_model (Pluto / LibreSDR / прочие).
 function PlutoModelName(const HwModel: string): string;
@@ -15,6 +24,8 @@ function FreqToBandIdx(Hz: Double; Pluto: Boolean = False): Integer;
 function BandName(Idx: Integer; Pluto: Boolean = False): string;
 // Частота по умолчанию при входе в диапазон (если нет сохранённой/в диапазоне).
 function BandDefaultFreq(Idx: Integer; Pluto: Boolean = False): Double;
+// Полный band-план активного бэкенда (имена + дефолтные частоты).
+function BuildBandPlan(Pluto: Boolean): TBandPlanArray;
 
 implementation
 
@@ -105,4 +116,23 @@ begin
   if Pluto then Result := VU_DEF[Idx] else Result := HF_DEF[Idx];
 end;
 
+function BuildBandPlan(Pluto: Boolean): TBandPlanArray;
+var i: Integer;
+begin
+  SetLength(Result, BAND_COUNT);
+  for i := 0 to BAND_COUNT - 1 do
+  begin
+    if Pluto then
+    begin
+      Result[i].Name   := VU_NAMES[i];
+      Result[i].FreqHz := VU_DEF[i];
+    end
+    else
+    begin
+      Result[i].Name   := HF_NAMES[i];
+      Result[i].FreqHz := HF_DEF[i];
+    end;
+  end;
+end;
+
 end.