feat: QO-100 beacon AO-40 FEC decode end-to-end (Milestone 2)

Full chain now decodes the QO-100 central beacon to 256-byte AO-40 frames
on-air (frames>0, RS errors=0). Builds on M1 (stable BPSK demod).

FEC backend (BeaconFEC.pas, TBeaconFEC):
- AO-40 FEC: distributed sync (65 bit, step 80) -> 80x65 deinterleave ->
  Viterbi r=1/2 k=7 -> CCSDS descramble -> 2x RS(160,128). Links system
  libfec (Karn) load-time (libfec.so/.dll/.dylib). Viterbi AO-40 [0x4F,-0x6D]
  remapped to libfec [0x6D,0x4F]. Validated against gr-satellites reference
  vectors (fectest2: exact 256-byte frame, 0 mismatches).

DBPSK Manchester frontend (BeaconDecoder.pas):
- Chip-rate (800) processing: RRC matched filter -> ML signal-times-slope
  timing recovery -> Costas -> Manchester combine (block phase select) ->
  differential decode -> soft symbols to FEC.
- Carrier acquisition: squaring-FFT estimates the residual (carrier at +-pi/chip
  defeats decision-directed Costas), one-shot pulls it to DC via residual NCO.
- Costas frequency offload into pre-RRC NCO (with deadband) tracks LNB drift
  without hitting the +-pi Costas clamp.
- ML TED replaces Gardner, which degenerates on the Manchester chip stream.

Temporary on-air diagnostics retained (IQ dump + STATE log) pending wider
signal validation; to be removed before final cleanup.

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

fectest2.lpr

@@ -0,0 +1,104 @@
+program fectest2;
+{$MODE Delphi}
+{
+  Валидация TBeaconFEC против эталонных тест-векторов gr-satellites
+  (python/components/deframers/qa_ao40_fec_deframer_*). Гоним поток мягких
+  символов через PushSoftSymbol и сверяем выданный 256-байтовый кадр с эталоном.
+  Решает вопрос конвенции Viterbi (libfec [0x6D,0x4F] vs AO-40 [0x4F,-0x6D]).
+}
+uses SysUtils, Classes, BeaconFEC;
+
+const
+  GR = '/home/vladimir/Документы/source/gr-satellites/python/components/deframers/';
+  SymPath = GR + 'qa_ao40_fec_deframer_symbols.f32';
+
+  // qa_ao40_fec_deframer.py: финальный кадр (256 байт)
+  FrameRef: array[0..255] of Byte = (
+    137, 0, 0, 0, 0, 0, 0, 0, 0, 31, 204, 0, 206, 2, 209, 0, 0,
+    7, 8, 9, 9, 0, 0, 5, 1, 1, 0, 64, 19, 47, 200, 242, 92,
+    143, 52, 35, 243, 186, 11, 93, 98, 116, 81, 199, 234, 250,
+    105, 74, 154, 159, 0, 9, 239, 160, 31, 244, 167, 234, 74,
+    198, 143, 17, 64, 17, 30, 16, 247, 1, 62, 32, 100, 0, 215,
+    139, 248, 215, 148, 200, 147, 168, 42, 218, 82, 166, 14, 88,
+    14, 200, 15, 78, 1, 29, 32, 90, 0, 219, 148, 168, 170, 138,
+    152, 19, 172, 105, 10, 166, 168, 16, 230, 16, 146, 15, 184,
+    1, 80, 32, 100, 0, 215, 150, 168, 193, 139, 72, 37, 171, 169,
+    202, 206, 157, 16, 118, 15, 201, 16, 85, 1, 58, 32, 90, 0, 215,
+    151, 41, 8, 140, 72, 79, 169, 106, 90, 242, 164, 16, 57, 15,
+    123, 15, 134, 1, 73, 32, 100, 0, 215, 148, 8, 208, 138, 216,
+    42, 173, 106, 90, 126, 180, 14, 83, 14, 155, 14, 183, 1, 9, 32,
+    90, 0, 219, 153, 168, 242, 143, 232, 56, 175, 170, 138, 194,
+    158, 14, 222, 15, 72, 14, 49, 1, 49, 32, 90, 0, 206, 155, 200,
+    255, 136, 104, 27, 178, 106, 90, 202, 167, 15, 195, 14, 116, 14,
+    88, 1, 52, 32, 90, 0, 215, 155, 57, 27, 151, 184, 197, 176, 43,
+    58, 214, 181, 1, 107, 0, 106, 2, 158, 0, 3, 32, 19, 0);
+
+type
+  TFrameChecker = class
+    Got:    Boolean;
+    Match:  Boolean;
+    NErr:   Integer;
+    RSErr:  Integer;
+    procedure OnFrame(const Frame: TBeaconFrame; RSErrors: Integer);
+  end;
+
+procedure TFrameChecker.OnFrame(const Frame: TBeaconFrame; RSErrors: Integer);
+var i, e: Integer;
+begin
+  if Got then Exit;        // берём первый кадр
+  Got := True;
+  RSErr := RSErrors;
+  e := 0;
+  for i := 0 to 255 do
+    if Frame[i] <> FrameRef[i] then Inc(e);
+  NErr := e;
+  Match := (e = 0);
+end;
+
+var
+  fec: TBeaconFEC;
+  chk: TFrameChecker;
+  fs: TFileStream;
+  n, i: Integer;
+  buf: array of Single;
+begin
+  if not FileExists(SymPath) then
+  begin
+    WriteLn('symbols file not found: ', SymPath); Halt(2);
+  end;
+  fs := TFileStream.Create(SymPath, fmOpenRead);
+  try
+    n := fs.Size div 4;
+    SetLength(buf, n);
+    fs.ReadBuffer(buf[0], n * 4);
+  finally
+    fs.Free;
+  end;
+  WriteLn('loaded ', n, ' soft symbols');
+
+  chk := TFrameChecker.Create;
+  fec := TBeaconFEC.Create;
+  try
+    fec.OnFrame := chk.OnFrame;
+    for i := 0 to n - 1 do
+      fec.PushSoftSymbol(buf[i]);
+
+    WriteLn('frames decoded: ', fec.Frames);
+    if not chk.Got then
+    begin
+      WriteLn('==> FAIL: no frame decoded (sync not found / RS uncorrectable)');
+      Halt(1);
+    end;
+    WriteLn(Format('frame: %d/256 byte mismatches, RS errors=%d', [chk.NErr, chk.RSErr]));
+    if chk.Match then
+      WriteLn('==> PASS: frame matches gr-satellites reference')
+    else
+    begin
+      WriteLn('==> FAIL: frame does not match reference');
+      Halt(1);
+    end;
+  finally
+    fec.Free;
+    chk.Free;
+  end;
+end.