web: fix A=B/SWAP VFO ops, wire attenuator, TUN button, FNP filter overlay

- Add freq_a command: sets VFO A regardless of active VFO; fixes A=B and
  SWAP when VFO B is active (prev. sent freq_b which overwrote wrong VFO)
- Add pend("freq") to B=A / A=B / SWAP to guard local display during round-trip
- RX step attenuator: HPSDRNetwork.SetStepAtten → bytes 1442/1443 in HP packet;
  WebServer attn command; MainForm FAtten + SyncWebAttn; attSel.onchange in JS
- TUN mode: set_tun WebSocket command wired to ApplyTUN(); toneBtn toggles
  with on/off highlight and pending protection; tuning field in state JSON
- FNP button opens semi-transparent filter overlay (10 buttons, 5×2 grid)
  with mode-appropriate widths (SSB/CW/AM/FM); active filter highlighted;
  cur.filter_bw updated immediately on click so passband redraws within 50ms

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

WebServer.pas

@@ -126,6 +126,9 @@ type
   TWebCmdCenter    = procedure(Hz: Double) of object;
   TWebCmdMOX       = procedure(On_: Boolean) of object;
   TWebCmdDrive     = procedure(V: Integer) of object;
+  TWebCmdFreqA     = procedure(Hz: Double) of object;
+  TWebCmdAttn      = procedure(Idx: Integer) of object;
+  TWebCmdTun       = procedure(On_: Boolean) of object;
 
   // ── Главный класс сервера ─────────────────────────────────────────────────
   TWebServer = class
@@ -210,6 +213,11 @@ type
     FOnDrive:     TWebCmdDrive;
     FTransmitting: Boolean;
     FDriveLevel:   Integer;
+    FOnFreqA:     TWebCmdFreqA;
+    FOnAttn:      TWebCmdAttn;
+    FAttnIdx:     Integer;
+    FOnTun:       TWebCmdTun;
+    FTuning:      Boolean;
 
     FWebClientActive: Boolean;
 
@@ -253,7 +261,8 @@ type
       NRMode, NBMode: Integer; SNB, ANF: Boolean;
       CenterHz: Double; FilterIdx: Integer;
       VfoB: Double; ActiveVfo: Integer;
-      Transmitting: Boolean; DriveLevel: Integer);
+      Transmitting: Boolean; DriveLevel: Integer;
+      AttnIdx: Integer; Tuning: Boolean);
 
     property WebClientActive: Boolean read FWebClientActive;
 
@@ -279,6 +288,9 @@ type
     property OnCenter:    TWebCmdCenter    read FOnCenter    write FOnCenter;
     property OnMOX:       TWebCmdMOX       read FOnMOX       write FOnMOX;
     property OnDrive:     TWebCmdDrive     read FOnDrive     write FOnDrive;
+    property OnFreqA:     TWebCmdFreqA     read FOnFreqA     write FOnFreqA;
+    property OnAttn:      TWebCmdAttn      read FOnAttn      write FOnAttn;
+    property OnTun:       TWebCmdTun       read FOnTun       write FOnTun;
   end;
 
 implementation
@@ -1004,6 +1016,26 @@ begin
     if V > 100 then V := 100;
     FStateLock.Enter; FDriveLevel := V; FStateLock.Leave;
     if Assigned(FOnDrive) then FOnDrive(V);
+  end
+  else if Cmd = 'set_tun' then
+  begin
+    On_ := JsonGetBool(Json, 'on', FTuning);
+    FStateLock.Enter; FTuning := On_; FStateLock.Leave;
+    if Assigned(FOnTun) then FOnTun(On_);
+  end
+  else if Cmd = 'freq_a' then
+  begin
+    HzF := JsonGetFloat(Json, 'hz', FFreq);
+    FStateLock.Enter; FFreq := HzF; FStateLock.Leave;
+    if Assigned(FOnFreqA) then FOnFreqA(HzF);
+  end
+  else if Cmd = 'attn' then
+  begin
+    Idx := JsonGetInt(Json, 'idx', FAttnIdx);
+    if Idx < 0 then Idx := 0;
+    if Idx > 2 then Idx := 2;
+    FStateLock.Enter; FAttnIdx := Idx; FStateLock.Leave;
+    if Assigned(FOnAttn) then FOnAttn(Idx);
   end;
 end;
 
@@ -1101,7 +1133,7 @@ begin
       '"wf_agc":%s,"wf_nf":%s,"band_idx":%d,"smeter_dbm":%.1f,' +
       '"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}',
+      '"transmitting":%s,"drive":%d,"attn_idx":%d,"tuning":%s}',
       [FFreq, FVfoB, FActiveVfo,
        FMode, MODE_N[FMode mod 8],
        FFilterIdx, FFilterBW,
@@ -1121,7 +1153,9 @@ begin
        BoolToStr(FANF,        'true', 'false'),
        BoolToStr(FConnected,  'true', 'false'),
        BoolToStr(FTransmitting, 'true', 'false'),
-       FDriveLevel
+       FDriveLevel,
+       FAttnIdx,
+       BoolToStr(FTuning, 'true', 'false')
       ]);
   finally
     FStateLock.Leave;
@@ -1187,7 +1221,8 @@ procedure TWebServer.PushSpectrum(
   NRMode, NBMode: Integer; SNB, ANF: Boolean;
   CenterHz: Double; FilterIdx: Integer;
   VfoB: Double; ActiveVfo: Integer;
-  Transmitting: Boolean; DriveLevel: Integer);
+  Transmitting: Boolean; DriveLevel: Integer;
+  AttnIdx: Integer; Tuning: Boolean);
 var N, i: Integer;
 begin
   if not FRunning then Exit;
@@ -1221,6 +1256,8 @@ begin
     FActiveVfo    := ActiveVfo;
     FTransmitting := Transmitting;
     FDriveLevel   := DriveLevel;
+    FAttnIdx      := AttnIdx;
+    FTuning       := Tuning;
   finally
     FStateLock.Leave;
   end;