Workaround for FPC bug #33006

- Fix FPC bug #33006: replace record constructor chaining with Init procedures

Overloaded record constructors in TBigInteger that chained to other
Create() overloads triggered FPC bug #33006, where managed-type fields
(FMagnitude: TCryptoLibUInt32Array) are silently lost. The chained
constructor call creates a temporary record in FPC; when that temporary
is finalized, dynamic array reference counts drop to zero and the data
is freed, leaving the caller's record with nil/empty managed fields.

Introduced three private Init procedures (InitFromString, InitFromBytes,
InitFromSignedBytes) that contain the actual initialization logic. All
10 affected constructors now delegate to the appropriate Init procedure
instead of chaining Create -> Create. Procedures operate directly on
Self, avoiding the temporary-record codegen path entirely.

CryptoLib/src/Math/ClpBigInteger.pas

@@ -109,6 +109,13 @@ type
     function AddToMagnitude(const AMagToAdd: TCryptoLibUInt32Array): TBigInteger;
     constructor Create(const ASignum: Int32; const AMag: TCryptoLibUInt32Array; const ACheckMag: Boolean); overload;
 
+    // Private init procedures (workaround for FPC bug #33006 - overloaded record
+    // constructor chaining loses managed-type fields). These are called by the
+    // public constructors instead of chaining Create -> Create.
+    procedure InitFromString(const AValue: String; const ARadix: Int32);
+    procedure InitFromBytes(const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32; const ABigEndian: Boolean);
+    procedure InitFromSignedBytes(const ASign: Int32; const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32; const ABigEndian: Boolean);
+
     // Private class helper functions
     class function PopCount(const AValue: UInt32): Int32; static;
     class function BitLen(const AValue: Byte): Int32; overload; static;
@@ -1344,10 +1351,15 @@ end;
 
 constructor TBigInteger.Create(const AValue: String);
 begin
-  Create(AValue, 10);
+  InitFromString(AValue, 10);
 end;
 
 constructor TBigInteger.Create(const AValue: String; const ARadix: Int32);
+begin
+  InitFromString(AValue, ARadix);
+end;
+
+procedure TBigInteger.InitFromString(const AValue: String; const ARadix: Int32);
 var
   LStr: String;
   LIndex, LChunk, LNext: Int32;
@@ -1492,20 +1504,25 @@ end;
 
 constructor TBigInteger.Create(const ABytes: TCryptoLibByteArray);
 begin
-  Create(ABytes, 0, System.Length(ABytes), True);
+  InitFromBytes(ABytes, 0, System.Length(ABytes), True);
 end;
 
 constructor TBigInteger.Create(const ABytes: TCryptoLibByteArray; const ABigEndian: Boolean);
 begin
-  Create(ABytes, 0, System.Length(ABytes), ABigEndian);
+  InitFromBytes(ABytes, 0, System.Length(ABytes), ABigEndian);
 end;
 
 constructor TBigInteger.Create(const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32);
 begin
-  Create(ABytes, AOffset, ALength, True);
+  InitFromBytes(ABytes, AOffset, ALength, True);
 end;
 
 constructor TBigInteger.Create(const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32; const ABigEndian: Boolean);
+begin
+  InitFromBytes(ABytes, AOffset, ALength, ABigEndian);
+end;
+
+procedure TBigInteger.InitFromBytes(const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32; const ABigEndian: Boolean);
 var
   LSign: Int32;
 begin
@@ -1523,20 +1540,25 @@ end;
 
 constructor TBigInteger.Create(const ASign: Int32; const ABytes: TCryptoLibByteArray);
 begin
-  Create(ASign, ABytes, 0, System.Length(ABytes), True);
+  InitFromSignedBytes(ASign, ABytes, 0, System.Length(ABytes), True);
 end;
 
 constructor TBigInteger.Create(const ASign: Int32; const ABytes: TCryptoLibByteArray; const ABigEndian: Boolean);
 begin
-  Create(ASign, ABytes, 0, System.Length(ABytes), ABigEndian);
+  InitFromSignedBytes(ASign, ABytes, 0, System.Length(ABytes), ABigEndian);
 end;
 
 constructor TBigInteger.Create(const ASign: Int32; const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32);
 begin
-  Create(ASign, ABytes, AOffset, ALength, True);
+  InitFromSignedBytes(ASign, ABytes, AOffset, ALength, True);
 end;
 
 constructor TBigInteger.Create(const ASign: Int32; const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32; const ABigEndian: Boolean);
+begin
+  InitFromSignedBytes(ASign, ABytes, AOffset, ALength, ABigEndian);
+end;
+
+procedure TBigInteger.InitFromSignedBytes(const ASign: Int32; const ABytes: TCryptoLibByteArray; const AOffset, ALength: Int32; const ABigEndian: Boolean);
 begin
   if (ASign < -1) or (ASign > 1) then
     raise EFormatCryptoLibException.Create(SInvalidSignValue);