fix: zstd with sharding (#56)

`zstd` would try end decode the entire shard instead of a subchunk. The added test fails without the patch with:
`ZarrV3Test.testShardingWithZstdCodecReadWrite:225 » Zstd Destination buffer is too small`

Author: LDeakin

src/main/java/dev/zarr/zarrjava/v3/codec/core/ZstdCodec.java

@@ -7,6 +7,7 @@
 import com.github.luben.zstd.ZstdCompressCtx;
 import dev.zarr.zarrjava.ZarrException;
 import dev.zarr.zarrjava.core.codec.BytesBytesCodec;
+import dev.zarr.zarrjava.utils.Utils;
 import dev.zarr.zarrjava.v3.ArrayMetadata;
 import dev.zarr.zarrjava.v3.codec.Codec;
 
@@ -28,7 +29,7 @@ public ZstdCodec(
 
     @Override
     public ByteBuffer decode(ByteBuffer compressedBytes) throws ZarrException {
-        byte[] compressedArray = compressedBytes.array();
+        byte[] compressedArray = Utils.toArray(compressedBytes);
 
         long originalSize = Zstd.getFrameContentSize(compressedArray);
         if (originalSize == 0) {
@@ -41,7 +42,7 @@ public ByteBuffer decode(ByteBuffer compressedBytes) throws ZarrException {
 
     @Override
     public ByteBuffer encode(ByteBuffer chunkBytes) throws ZarrException {
-        byte[] arr = chunkBytes.array();
+        byte[] arr = Utils.toArray(chunkBytes);
         byte[] compressed;
         try (ZstdCompressCtx ctx = new ZstdCompressCtx()) {
             ctx.setLevel(configuration.level);

src/test/java/dev/zarr/zarrjava/ZarrV3Test.java

@@ -206,6 +206,27 @@ public void testZstdCodecReadWrite(int clevel, boolean checksum) throws ZarrExce
         Assertions.assertArrayEquals(testData, (int[]) result.get1DJavaArray(ucar.ma2.DataType.UINT));
     }
 
+    @Test
+    public void testShardingWithZstdCodecReadWrite() throws ZarrException, IOException {
+        int[] testData = new int[16 * 16 * 16];
+        Arrays.setAll(testData, p -> p);
+
+        StoreHandle storeHandle = new FilesystemStore(TESTOUTPUT).resolve("testShardingWithZstdCodecReadWrite");
+        ArrayMetadataBuilder builder = Array.metadataBuilder()
+                .withShape(16, 16, 16)
+                .withDataType(DataType.UINT32)
+                .withChunkShape(8, 8, 8)
+                .withFillValue(0)
+                .withCodecs(c -> c.withSharding(new int[]{2, 4, 8}, c1 -> c1.withZstd()));
+        Array writeArray = Array.create(storeHandle, builder.build());
+        writeArray.write(ucar.ma2.Array.factory(ucar.ma2.DataType.UINT, new int[]{16, 16, 16}, testData));
+
+        Array readArray = Array.open(storeHandle);
+        ucar.ma2.Array result = readArray.read();
+
+        Assertions.assertArrayEquals(testData, (int[]) result.get1DJavaArray(ucar.ma2.DataType.UINT));
+    }
+
     @Test
     public void testTransposeCodec() throws ZarrException {
         ucar.ma2.Array testData = ucar.ma2.Array.factory(ucar.ma2.DataType.UINT, new int[]{2, 3, 3}, new int[]{