feat: bundle opencode plugin as open-code-review passthru + HM module

- packages/open-code-review/opencode-plugin.nix: builds the plugin TS file
  plus runtime node_modules from the plugin's package-lock.json into
  share/open-code-review/opencode (exposed as passthru.opencode-plugin,
  same source rev as the CLI so versions stay locked)
- modules/open-code-review-hm.nix: homeManagerModules.default with
  programs.open-code-review.{enable,opencode.enable} — symlinks the plugin
  and node_modules into ~/.config/opencode/plugins/ and installs the CLI
- flake.nix: expose homeManagerModules.default

Note: upstream declares the plugin SDKs as devDependencies, so the
lockfile install must not use --omit=dev.

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <noreply@codebuff.com>

flake.nix

@@ -57,5 +57,9 @@
       nixosModules.default = {
         nixpkgs.overlays = [ self.overlays.default ];
       };
+
+      homeManagerModules.default = {
+        imports = [ ./modules/open-code-review-hm.nix ];
+      };
     };
 }