Add configurable VFO frequency range with GHz support

- Settings > Display: new "VFO Display" control to select max frequency
  range (999 MHz / 9.999 GHz / 99.999 GHz), persisted as freq_mhz_digits
- FreqDisplay: extend digit map [0..10] to support up to 11 digit positions;
  keyboard navigation adapts to MinMhzDigits dynamically
- MainForm/LayoutTopVfoBlock: VFO panel width scales automatically with
  selected digit count using dynamic text measurement
- Web VFO: fix broken HTML (class attr not closed before data-s — wheel and
  hover were completely non-functional); rewrite fmtVfo to use variable MHz
  digit count synced from server state; fix missing </span> for .vfo-hz
- WebServer: publish freq_mhz_digits in state JSON; updated from
  ApplyFreqMhzDigits so desktop and web stay in sync
- Fix Int32 overflow on frequencies above ~2.15 GHz: CATEngine.Pad V param
  Int64, FormatFreq/FormatFreqSV Mhz var Int64 (Mhz*1000000 overflowed)

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

FreqDisplay.pas

@@ -36,8 +36,8 @@ type
     FCenterText: Boolean;
     FOnChange:    TFreqChangeEvent;
 
-    FHoverDigit:  Integer;          // 0=единицы .. 8=100МГц, -1=нет
-    FDigitX:      array[0..8] of Integer;  // X левого края каждой цифры
+    FHoverDigit:  Integer;          // 0=единицы .. 10=10ГГц, -1=нет
+    FDigitX:      array[0..10] of Integer; // X левого края каждой цифры
     FDigitW:      Integer;
     FCharH:       Integer;
 
@@ -125,7 +125,7 @@ var
 begin
   Result := -1;
   if FDigitW = 0 then Exit;
-  for i := 0 to 8 do
+  for i := 0 to 10 do
     if (X >= FDigitX[i]) and (X < FDigitX[i] + FDigitW) then
     begin
       Result := i;
@@ -137,14 +137,14 @@ end;
 // Цифры нумеруются справа налево: digit0=единицы, digit8=сотни млн
 procedure TFreqDisplay.BuildDigitMap(const S: string; StartX: Integer);
 var
-  Xs:    array[0..11] of Integer;  // X каждого символа строки (макс 12 симв)
+  Xs:    array[0..13] of Integer;  // X каждого символа строки (макс 14 симв)
   ci:    Integer;
   xi:    Integer;
   dIdx:  Integer;
   len:   Integer;
 begin
   len := Length(S);
-  if len > 12 then len := 12;
+  if len > 13 then len := 13;
 
   xi := StartX;
   for ci := 0 to len - 1 do
@@ -159,7 +159,7 @@ begin
   begin
     if S[ci + 1] <> '.' then
     begin
-      if dIdx <= 8 then
+      if dIdx <= 10 then
         FDigitX[dIdx] := Xs[ci];
       Inc(dIdx);
     end;
@@ -185,7 +185,7 @@ var
   ch:      Char;
   dIdx:    Integer;
   col:     TColor;
-  DiChar:  array[0..11] of Integer;
+  DiChar:  array[0..13] of Integer;
   tmpIdx:  Integer;
   len:     Integer;
 begin
@@ -234,7 +234,7 @@ begin
 
   // Строим обратную карту символ → digit index
   len := Length(S);
-  if len > 12 then len := 12;
+  if len > 13 then len := 13;
   tmpIdx := 0;
   for ci := len - 1 downto 0 do
   begin
@@ -385,7 +385,7 @@ begin
     VK_DOWN: begin ChangeByDigit(d, -1); Key := 0; end;
     VK_LEFT: begin
                if FHoverDigit < 0 then FHoverDigit := 3;
-               if FHoverDigit < 8 then Inc(FHoverDigit);
+               if FHoverDigit < FMinMhzDigits + 5 then Inc(FHoverDigit);
                Invalidate; Key := 0;
              end;
     VK_RIGHT: begin