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>

WebServer.pas

@@ -241,7 +241,8 @@ type
     FAttnIdx:     Integer;
     FOnTun:       TWebCmdTun;
     FTuning:      Boolean;
-    FDuplex:      Boolean;
+    FDuplex:         Boolean;
+    FFreqMhzDigits:  Integer;     // 3=999MHz, 4=9.999GHz, 5=99.999GHz
     FXvtrBands:   TWebXvtrArray;  // список enabled XVTR (для web-UI)
     FCurrentXvtr: Integer;        // -1 = HF, иначе индекс активного XVTR
     FOnXvtrBand:  TWebCmdXvtrBand;
@@ -292,6 +293,7 @@ type
       AttnIdx: Integer; Tuning: Boolean; Duplex: Boolean);
 
     property WebClientActive: Boolean read FWebClientActive;
+    property FreqMhzDigits: Integer read FFreqMhzDigits write FFreqMhzDigits;
 
     property OnFreq:   TWebCmdFreq   read FOnFreq   write FOnFreq;
     property OnMode:   TWebCmdMode   read FOnMode   write FOnMode;
@@ -419,7 +421,8 @@ begin
   FVolume  := 70;
   FSMeter  := -120;
   FBandIdx := 5;
-  FCurrentXvtr := -1;
+  FCurrentXvtr  := -1;
+  FFreqMhzDigits := 3;
   SetLength(FXvtrBands, 0);
 end;
 
@@ -1233,7 +1236,7 @@ begin
       '"running":%s,"mute":%s,"ctun":%s,' +
       '"nr_mode":%d,"nr":%s,"nb_mode":%d,"nb":%s,"snb":%s,"anf":%s,"connected":%s,' +
       '"transmitting":%s,"drive":%d,"attn_idx":%d,"tuning":%s,"dup":%s,' +
-      '"xvtr_current":%d,"xvtr_bands":%s}',
+      '"xvtr_current":%d,"xvtr_bands":%s,"freq_mhz_digits":%d}',
       [FFreq, FVfoB, FActiveVfo,
        FMode, MODE_N[FMode mod 8],
        FFilterIdx, FFilterBW,
@@ -1257,7 +1260,7 @@ begin
        FAttnIdx,
        BoolToStr(FTuning,  'true', 'false'),
        BoolToStr(FDuplex, 'true', 'false'),
-       FCurrentXvtr, XvtrJson
+       FCurrentXvtr, XvtrJson, FFreqMhzDigits
       ], FS);
   finally
     FStateLock.Leave;