Use TConverters for endian-safe block loads in Blake3 and XXHash3 dispatch

Replace raw memory copies and unchecked PUInt64 loads in scalar dispatch
fallbacks with TConverters helpers so byte streams are interpreted as
little-endian words consistently with the rest of HashLib.

- HlpBlake3Dispatch: load HashMany compress blocks via le32_copy instead
  of System.Move
- HlpXXHash3Dispatch: read input/secret bytes in scalar Accumulate512,
  ScrambleAcc, and InitSecret via ReadBytesAsUInt64LE

Behavior is unchanged on little-endian targets; big-endian portability
is improved. SIMD/asm paths are untouched.

Author: Xor-el

HashLib/src/Crypto/HlpBlake3Dispatch.pas

@@ -26,6 +26,7 @@ implementation
 
 uses
   HlpBits,
+  HlpConverters,
   HlpCpuFeatures,
   HlpSimdLevels;
 
@@ -579,8 +580,7 @@ procedure Blake3_HashMany_Scalar(AInput, AKey, AOut: Pointer;
     // Process 16 blocks per chunk
     for LBlock := 0 to 15 do
     begin
-      // Convert block bytes to words (assume little-endian)
-      System.Move(LPInput^, LBlockWords[0], 64);
+      TConverters.le32_copy(LPInput, 0, @LBlockWords[0], 0, 64);
 
       // Set flags for this block
       LBlockFlags := AFlags;

HashLib/src/Hash64/HlpXXHash3Dispatch.pas

@@ -22,6 +22,7 @@ interface
 implementation
 
 uses
+  HlpConverters,
   HlpCpuFeatures,
   HlpSimdLevels;
 
@@ -48,8 +49,8 @@ procedure XXH3_Accumulate512_Scalar(AAcc: Pointer; AInput: Pointer;
   LPSecret := PByte(ASecret);
   for I := 0 to XXH_ACC_NB - 1 do
   begin
-    LDataVal := PUInt64(LPInput + I * 8)^;
-    LDataKey := LDataVal xor PUInt64(LPSecret + I * 8)^;
+    LDataVal := TConverters.ReadBytesAsUInt64LE(LPInput, I * 8);
+    LDataKey := LDataVal xor TConverters.ReadBytesAsUInt64LE(LPSecret, I * 8);
     PUInt64(PByte(LPAcc) + (I xor 1) * 8)^ :=
       PUInt64(PByte(LPAcc) + (I xor 1) * 8)^ + LDataVal;
     PUInt64(PByte(LPAcc) + I * 8)^ :=
@@ -69,7 +70,7 @@ procedure XXH3_ScrambleAcc_Scalar(AAcc: Pointer; ASecret: Pointer);
   LPSecret := PByte(ASecret);
   for I := 0 to XXH_ACC_NB - 1 do
   begin
-    LKey64 := PUInt64(LPSecret + I * 8)^;
+    LKey64 := TConverters.ReadBytesAsUInt64LE(LPSecret, I * 8);
     LAcc64 := PUInt64(PByte(LPAcc) + I * 8)^;
     LAcc64 := LAcc64 xor (LAcc64 shr 47);
     LAcc64 := LAcc64 xor LKey64;
@@ -88,8 +89,10 @@ procedure XXH3_InitSecret_Scalar(ACustomSecret: Pointer;
   LPDst := PByte(ACustomSecret);
   for I := 0 to (192 div 16) - 1 do
   begin
-    PUInt64(LPDst + 16 * I)^ := PUInt64(LPSrc + 16 * I)^ + ASeed;
-    PUInt64(LPDst + 16 * I + 8)^ := PUInt64(LPSrc + 16 * I + 8)^ - ASeed;
+    PUInt64(LPDst + 16 * I)^ :=
+      TConverters.ReadBytesAsUInt64LE(LPSrc, 16 * I) + ASeed;
+    PUInt64(LPDst + 16 * I + 8)^ :=
+      TConverters.ReadBytesAsUInt64LE(LPSrc, 16 * I + 8) - ASeed;
   end;
 end;