build slsk-batchdl

using dotnet 8 thanks to help from claude, not sure if i'm actually
doing any of this correctly

pkgs/slsk-batchdl/package.nix

@@ -0,0 +1,39 @@
+{
+  lib,
+  buildDotnetModule,
+  fetchFromGitHub,
+  dotnetCorePackages,
+}:
+
+buildDotnetModule rec {
+  pname = "slsk-batchdl";
+  version = "2.4.7";
+
+  src = fetchFromGitHub {
+    owner = "fiso64";
+    repo = "slsk-batchdl";
+    rev = "v${version}";
+    sha256 = "sha256-P7V7YJUA1bkfp13Glb1Q+NJ7iTya/xgO1TM88z1Nddc=";
+  };
+
+  projectFile = "slsk-batchdl/slsk-batchdl.csproj";
+  nugetDeps = ./nuget-deps.nix;
+
+  dotnet-sdk = dotnetCorePackages.sdk_8_0;
+  dotnet-runtime = dotnetCorePackages.runtime_8_0;
+
+  # Patch the project file to use .NET 8
+  postPatch = ''
+    substituteInPlace slsk-batchdl/slsk-batchdl.csproj \
+      --replace-fail "net6.0" "net8.0"
+  '';
+
+  doCheck = false;
+
+  meta = with lib; {
+    description = "A batch downloader for Soulseek";
+    homepage = "https://github.com/fiso64/slsk-batchdl";
+    platforms = platforms.linux;
+    mainProgram = "slsk-batchdl";
+  };
+}