Add FM mode improvements: NFM/FM filters, CTCSS, squelch; ADC and web settings

FM modulation:
- Replace 10 generic FM filter buttons with NFM (2.5kHz dev/11kHz BW) and FM
  (5.0kHz dev/16kHz BW); deviation applied to both RX and TX via WDSP
- Add FM squelch panel (SQL toggle + slider 0..100, per-band save/restore)
  with WDSP SetRXAFMSQRun/SetRXAFMSQThreshold (threshold = level/200.0)
- Add CTCSS panel with on/off toggle and custom flat-button tone picker popup
  (38 standard tones 67.0..250.3 Hz, default 67.0); tone selection and enable
  state saved per band via SetTXACTCSS*
- FM panels (SQL, CTCSS) shown only in FM mode, layout via RelayoutBelowBands
- PanelFilter height shrinks in FM mode so panels sit tight below filters
- FlatButton: handle CMTextChanged to invalidate on Caption change

ADC settings (Dither/Random):
- Add DitherEnabled/RandomEnabled to TGlobalSettings (default true)
- Pass as bitmask to ConfigureDDCs DDC Specific packet bytes 5/6
- Exposed in Settings → Advanced tab with live apply via ApplyADCSettings

Web server settings:
- Add TWebSettings (enabled, port, bind_addr, user, pass) stored globally
- WebServer: configurable port/bind IP via ParseIPv4; Reconfigure method
- Exposed in Settings → Advanced tab with live apply via ApplyWebSettings

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

WDSPEngine.pas

@@ -360,6 +360,8 @@ type
     procedure SetNB(Enable: Boolean);
     procedure SetSNB(Enable: Boolean);
     procedure SetANF(Enable: Boolean);
+    procedure SetRXFMDeviation(Deviation: Double);
+    procedure SetFMSquelch(Enable: Boolean; Level: Integer);
     procedure SetVolume(Vol: Double);
     procedure SetMute(Mute: Boolean);
 
@@ -1513,6 +1515,26 @@ begin
   ApplyANFState;
 end;
 
+procedure TWDSPEngine.SetRXFMDeviation(Deviation: Double);
+begin
+  if not FInitialized then Exit;
+  SetRXAFMDeviation(RXA_CHAN, Deviation);
+end;
+
+procedure TWDSPEngine.SetFMSquelch(Enable: Boolean; Level: Integer);
+var Threshold: Double;
+begin
+  if not FInitialized then Exit;
+  if Enable then
+  begin
+    Threshold := Level / 200.0;   // 0..100 → 0.0..0.5
+    SetRXAFMSQThreshold(RXA_CHAN, Threshold);
+    SetRXAFMSQRun(RXA_CHAN, 1);
+  end
+  else
+    SetRXAFMSQRun(RXA_CHAN, 0);
+end;
+
 procedure TWDSPEngine.SetVolume(Vol: Double);
 begin
   FVolume := Max(0.0, Min(1.0, Vol));