add libgen-mcp package

Library Genesis MCP server (jmrplens/libgen-mcp v2.0.1): federated book/paper search, download and read across LibGen and open-access sources. No account, API key or cookie required, unlike annas-mcp.

The flake's pinned nixpkgs only ships Go 1.26 and upstream needs Go 1.27, so package the prebuilt static release binaries (same approach as yarr).

packages/default.nix

@@ -22,6 +22,7 @@
   pinchflat-mcp = pkgs.callPackage ./pinchflat-mcp/package.nix { };
   audiobookshelf-mcp = pkgs.callPackage ./audiobookshelf-mcp/package.nix { };
   annas-mcp = pkgs.callPackage ./annas-mcp/package.nix { };
+  libgen-mcp = pkgs.callPackage ./libgen-mcp/package.nix { };
   bitwarden-mcp = pkgs.callPackage ./bitwarden-mcp/package.nix { };
   mcp-email-server = pkgs.callPackage ./mcp-email-server/package.nix { };
   namecheap-mcp = pkgs.callPackage ./namecheap-mcp/package.nix { };

packages/libgen-mcp/package.nix

@@ -0,0 +1,54 @@
+{
+  lib,
+  stdenv,
+  fetchurl,
+}:
+
+stdenv.mkDerivation rec {
+  pname = "libgen-mcp";
+  version = "2.0.1";
+
+  src = fetchurl (
+    {
+      x86_64-linux = {
+        url = "https://github.com/jmrplens/libgen-mcp/releases/download/v${version}/libgen-mcp-linux-amd64";
+        hash = "sha256-MN6DQ76AmGfaz/Xsyuk6EgFbHxf4TEcg5HXyVomn8G8=";
+      };
+      aarch64-linux = {
+        url = "https://github.com/jmrplens/libgen-mcp/releases/download/v${version}/libgen-mcp-linux-arm64";
+        hash = "sha256-qIkFGqEaohEnL99vbjM86JjFaHbV+A7vKNVSZg0G5Cg=";
+      };
+      x86_64-darwin = {
+        url = "https://github.com/jmrplens/libgen-mcp/releases/download/v${version}/libgen-mcp-darwin-amd64";
+        hash = "sha256-eeLfugTMCbvuyT3NzVQmBovarz0tOtOMsbNzAVKUTco=";
+      };
+      aarch64-darwin = {
+        url = "https://github.com/jmrplens/libgen-mcp/releases/download/v${version}/libgen-mcp-darwin-arm64";
+        hash = "sha256-xmKMeMJtOrqZwgTv7CvXiLEMib/XLvkQ3rCFTOyGU/Y=";
+      };
+    }
+    .${stdenv.hostPlatform.system} or (throw "libgen-mcp: unsupported system ${stdenv.hostPlatform.system}")
+  );
+
+  dontUnpack = true;
+
+  installPhase = ''
+    runHook preInstall
+    mkdir -p $out/bin
+    install -m755 $src $out/bin/${pname}
+    runHook postInstall
+  '';
+
+  meta = with lib; {
+    description = "MCP server for federated search, download and reading of books, papers, comics and standards across Library Genesis and open-access sources";
+    homepage = "https://github.com/jmrplens/libgen-mcp";
+    license = licenses.mit;
+    mainProgram = pname;
+    platforms = [
+      "x86_64-linux"
+      "aarch64-linux"
+      "x86_64-darwin"
+      "aarch64-darwin"
+    ];
+  };
+}