Phase 5 (batch 25a): de-dup telemetry fields + push web-client-active to core

Prep for moving the HP-status callback into the controller:
- Remove the duplicate FLast{SMeter,FwdW,SWR,SupplyV,SupplyA,PLLLock}
  fields from MainForm; the controller (which already declared them) is
  now the sole owner. The UI-only S-meter ballistics (FSMeterPeak/Min/Avg)
  stay in MainForm.
- TWebServer gains an OnClientActiveChanged event (fired via a
  SetClientActive setter at the three client connect/disconnect points);
  MainForm mirrors it into FController.FWebClientActive. The lazy mirror
  in ApplyMOX/ApplyTUN is removed, so the flag is always current — needed
  for the HWPTT->SetMOX path that moves into the controller next.

Behaviour-preserving (the flag held the same value at MOX time before).

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

WebServer.pas

@@ -151,6 +151,9 @@ type
   // XVTR-band: web клиент кликнул кнопку трансвертера (Idx 0..CFG_XVTR_COUNT-1).
   // Idx=-1 — выход в HF.
   TWebCmdXvtrBand  = procedure(Idx: Integer) of object;
+  // Активность web-клиента изменилась (подключился/отключился последний клиент).
+  // Хозяин зеркалит это в ядро (FController.FWebClientActive) для выбора mic-source.
+  TWebClientActiveEvent = procedure(Active: Boolean) of object;
   // Один XVTR-слот для статуса (для отображения в web-bandSel).
   TWebXvtrInfo = record
     Idx: Integer;
@@ -294,6 +297,11 @@ type
     FSeqText:     string;
 
     FWebClientActive: Boolean;
+    FOnClientActiveChanged: TWebClientActiveEvent;
+
+    // Обновляет FWebClientActive и при изменении уведомляет хозяина. Вызывать
+    // под уже взятой блокировкой поля (FStateLock/FClientLock) — сам не лочит.
+    procedure SetClientActive(Value: Boolean);
 
     // ── Внутренние методы ──
     function  LoadOpus: Boolean;
@@ -346,6 +354,8 @@ type
       RXText, TXText, SeqText: string);
 
     property WebClientActive: Boolean read FWebClientActive;
+    property OnClientActiveChanged: TWebClientActiveEvent
+      read FOnClientActiveChanged write FOnClientActiveChanged;
     property FreqMhzDigits: Integer read FFreqMhzDigits write FFreqMhzDigits;
     property FMStepIdx: Integer read FFMStepIdx write FFMStepIdx;
 
@@ -980,7 +990,7 @@ begin
     Client.State := wsOpen;
 
     FStateLock.Enter;
-    FWebClientActive := True;
+    SetClientActive(True);
     FStateLock.Leave;
 
     Client.SendText(BuildStateJson);
@@ -1114,14 +1124,21 @@ begin
   end;
 
   FStateLock.Enter;
-  FWebClientActive := (FClientCount > 1);
+  SetClientActive(FClientCount > 1);
   FStateLock.Leave;
 
   RemoveClient(Client);
 end;
 
+procedure TWebServer.SetClientActive(Value: Boolean);
+begin
+  if FWebClientActive = Value then Exit;
+  FWebClientActive := Value;
+  if Assigned(FOnClientActiveChanged) then FOnClientActiveChanged(Value);
+end;
+
 procedure TWebServer.RemoveClient(Client: TWsClient);
-var i, j: Integer;
+var i, j: Integer; NewActive: Boolean;
 begin
   FClientLock.Enter;
   try
@@ -1134,10 +1151,11 @@ begin
         Dec(FClientCount);
         Break;
       end;
-    FWebClientActive := False;
+    NewActive := False;
     for i := 0 to FClientCount - 1 do
       if (FClients[i] <> nil) and (FClients[i].State = wsOpen) then
-      begin FWebClientActive := True; Break; end;
+      begin NewActive := True; Break; end;
+    SetClientActive(NewActive);
   finally
     FClientLock.Leave;
   end;