add browser mic TX: Opus-encoded mic audio from web client to WDSP TX chain

- Browser: AudioWorklet accumulates 960-sample frames, AudioEncoder encodes
  to Opus, sends binary WS frame 'M' + raw Opus packet
- Server: opcode $02 handler decodes Opus via libopus, calls OnWebMic callback
- MainForm: WebOnMic converts PSingle→Double, pushes to PushTXMicSamplesD;
  ApplyMOX switches mic source to txmsWeb when web client active, restores on TX-off
- WDSPEngine: added txmsWeb to TTXMicSource enum

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

WebServer.pas

@@ -103,6 +103,13 @@ type
   TOpus_encoder_ctl_set = function(st: POpusEncoder;
                                    request: Integer; value: Integer): Integer; cdecl;
 
+  POpusDecoder = Pointer;
+  TOpus_decoder_create  = function(Fs, channels: Integer;
+                                   error: PInteger): POpusDecoder; cdecl;
+  TOpus_decode_float    = function(st: POpusDecoder; data: PByte; len: Integer;
+                                   pcm: PSingle; frame_size, decode_fec: Integer): Integer; cdecl;
+  TOpus_decoder_destroy = procedure(st: POpusDecoder); cdecl;
+
   // ── Callbacks в MainForm ──────────────────────────────────────────────────
   TWebCmdFreq    = procedure(Hz: Double) of object;
   TWebCmdMode    = procedure(Mode: Integer) of object;
@@ -129,6 +136,7 @@ type
   TWebCmdFreqA     = procedure(Hz: Double) of object;
   TWebCmdAttn      = procedure(Idx: Integer) of object;
   TWebCmdTun       = procedure(On_: Boolean) of object;
+  TWebMicCB        = procedure(Samples: PSingle; Count: Integer) of object;
 
   // ── Главный класс сервера ─────────────────────────────────────────────────
   TWebServer = class
@@ -144,6 +152,12 @@ type
     FOpusBufPos:  Integer;
     FOpusOut:     array[0..3999] of Byte;
     FOpusReady:   Boolean;
+    // Opus decoder — для RX TX-mic аудио от браузера
+    FOpusDec:        POpusDecoder;
+    FOpusDecCreate:  TOpus_decoder_create;
+    FOpusDecDecode:  TOpus_decode_float;
+    FOpusDecDestroy: TOpus_decoder_destroy;
+    FOnWebMic:       TWebMicCB;
 
     // ── TCP ──
     FListenSock:  TSocket;
@@ -292,6 +306,7 @@ type
     property OnFreqA:     TWebCmdFreqA     read FOnFreqA     write FOnFreqA;
     property OnAttn:      TWebCmdAttn      read FOnAttn      write FOnAttn;
     property OnTun:       TWebCmdTun       read FOnTun       write FOnTun;
+    property OnWebMic:    TWebMicCB        read FOnWebMic    write FOnWebMic;
   end;
 
 implementation
@@ -423,6 +438,9 @@ begin
   FOpusDestroy := TOpus_encoder_destroy(GetProcAddress(FOpusLib, 'opus_encoder_destroy'));
   FOpusEncode  := TOpus_encode_float(   GetProcAddress(FOpusLib, 'opus_encode_float'));
   FOpusCtl     := TOpus_encoder_ctl_set(GetProcAddress(FOpusLib, 'opus_encoder_ctl'));
+  FOpusDecCreate  := TOpus_decoder_create( GetProcAddress(FOpusLib, 'opus_decoder_create'));
+  FOpusDecDecode  := TOpus_decode_float(   GetProcAddress(FOpusLib, 'opus_decode_float'));
+  FOpusDecDestroy := TOpus_decoder_destroy(GetProcAddress(FOpusLib, 'opus_decoder_destroy'));
 
   if not Assigned(FOpusCreate) or not Assigned(FOpusEncode) then
   begin
@@ -439,6 +457,14 @@ begin
   if Assigned(FOpusCtl) then
     FOpusCtl(FOpusEnc, 4002, OPUS_BITRATE);
 
+  // Декодер для TX mic (браузер → Opus → WDSP)
+  if Assigned(FOpusDecCreate) then
+  begin
+    Err := 0;
+    FOpusDec := FOpusDecCreate(OPUS_SAMPLE_RATE, OPUS_CHANNELS, @Err);
+    if Err <> 0 then FOpusDec := nil;
+  end;
+
   FOpusBufPos := 0;
   FOpusReady  := True;
   Result      := True;
@@ -449,6 +475,9 @@ begin
   if FOpusReady and Assigned(FOpusDestroy) and (FOpusEnc <> nil) then
     FOpusDestroy(FOpusEnc);
   FOpusEnc   := nil;
+  if Assigned(FOpusDec) and Assigned(FOpusDecDestroy) then
+    FOpusDecDestroy(FOpusDec);
+  FOpusDec   := nil;
   FOpusReady := False;
   if FOpusLib <> 0 then
   begin
@@ -664,6 +693,8 @@ var
   Consumed:      Integer;
   Raw:           array[0..8191] of Byte;
   RawLen:        Integer;
+  PcmBuf:        array[0..5759] of Single;  // 120ms max @ 48kHz (для RX TX-mic)
+  Decoded:       Integer;
 begin
   WsHandled := False;
   RawLen    := 0;
@@ -813,6 +844,18 @@ begin
             if PayLen > 0 then Move(Payload[0], Header[1], PayLen);
             ProcessCommand(Client, Header);
           end;
+        $02: // Binary — TX mic Opus frame: byte 'M' + raw Opus packet
+          begin
+            if (PayLen > 1) and (Payload[0] = Ord('M')) and
+               Assigned(FOpusDec) and Assigned(FOpusDecDecode) and
+               Assigned(FOnWebMic) then
+            begin
+              Decoded := FOpusDecDecode(FOpusDec, @Payload[1], PayLen - 1,
+                                        @PcmBuf[0], Length(PcmBuf), 0);
+              if Decoded > 0 then
+                FOnWebMic(@PcmBuf[0], Decoded);
+            end;
+          end;
         $08: // Close
           begin
             Client.State := wsClosed;