Remove legacy Brotli decompression support

Removed Brotli decompression logic from both CompressionHelpers and SnapshotConcatStream. Only ZstdSharp-based decompression is now supported for compressed streams. This simplifies the codebase and reduces dependency on Brotli.

Author: Vadim Belov

src/Octockup.Server/Helpers/CompressionHelpers.cs

@@ -1,5 +1,4 @@
 using EasyExtensions.Models.Enums;
-using System.IO.Compression;
 
 namespace Octockup.Server.Helpers
 {
@@ -21,15 +20,6 @@ public static Stream CreateDecompressionStream(Stream decrypted, bool leaveOpen
             return new ZstdSharp.DecompressionStream(decrypted, leaveOpen: leaveOpen);
         }
 
-        internal static BrotliStream CreateLegacyDecompressionStream(Stream decrypted, bool leaveOpen)
-        {
-            return new BrotliStream(
-                decrypted,
-                CompressionMode.Decompress,
-                leaveOpen: leaveOpen
-            );
-        }
-
         internal static bool ShouldCompressChunk(string fileNameOrPath, long chunkLength)
         {
             if (chunkLength < 1024)

src/Octockup.Server/Streams/SnapshotConcatStream.cs

@@ -79,7 +79,6 @@ private async Task<bool> MoveToNextChunkAsync()
             Stream decompressed = algorithm switch
             {
                 CompressionAlgorithm.None => decrypted,
-                CompressionAlgorithm.Brotli => CompressionHelpers.CreateLegacyDecompressionStream(decrypted, leaveOpen: false),
                 CompressionHelpers.Algorithm => CompressionHelpers.CreateDecompressionStream(decrypted, leaveOpen: false),
                 _ => throw new NotSupportedException($"Unsupported compression algorithm: {algorithm}"),
             };