feat: add opencode, comment-checker packages; update README and flake.lock

- Add opencode and comment-checker to home packages
- Package comment-checker via prebuilt GitHub Releases binaries
- Register comment-checker overlay and flake packages output
- Add flake.lock to pin dependency versions
- Update README to match actual repo structure
- Add Node.js version notes in languages.nix

pkgs/comment-checker/default.nix

@@ -0,0 +1,55 @@
+{ lib
+, stdenv
+, fetchurl
+, autoPatchelfHook
+}:
+
+let
+  version = "0.7.0";
+
+  # 预编译二进制来自 GitHub Releases（goreleaser 构建，tree-sitter 已静态链接）
+  srcs = {
+    "aarch64-darwin" = {
+      url = "https://github.com/code-yeongyu/go-claude-code-comment-checker/releases/download/v${version}/comment-checker_v${version}_darwin_arm64.tar.gz";
+      hash = "sha256-0woeTNx7MXraKsshJB7aTkpnfi9GQn9dJEy+/VUfDX8=";
+    };
+    "x86_64-linux" = {
+      url = "https://github.com/code-yeongyu/go-claude-code-comment-checker/releases/download/v${version}/comment-checker_v${version}_linux_amd64.tar.gz";
+      hash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+    };
+    "aarch64-linux" = {
+      url = "https://github.com/code-yeongyu/go-claude-code-comment-checker/releases/download/v${version}/comment-checker_v${version}_linux_arm64.tar.gz";
+      hash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+    };
+  };
+
+  platformSrc = srcs.${stdenv.hostPlatform.system} or (throw "Unsupported system: ${stdenv.hostPlatform.system}");
+in
+stdenv.mkDerivation {
+  pname = "comment-checker";
+  inherit version;
+
+  src = fetchurl {
+    inherit (platformSrc) url hash;
+  };
+
+  sourceRoot = ".";
+
+  nativeBuildInputs = lib.optionals stdenv.hostPlatform.isLinux [ autoPatchelfHook ];
+
+  unpackPhase = ''
+    tar -xzf $src
+  '';
+
+  installPhase = ''
+    install -Dm755 comment-checker $out/bin/comment-checker
+  '';
+
+  meta = with lib; {
+    description = "Multi-language comment detection hook for Claude Code / OpenCode";
+    homepage = "https://github.com/code-yeongyu/go-claude-code-comment-checker";
+    license = licenses.mit;
+    platforms = [ "aarch64-darwin" "x86_64-linux" "aarch64-linux" ];
+    mainProgram = "comment-checker";
+  };
+}