fix(opencode): add root index.js entrypoint for v2 directory-form registration

index.js

@@ -0,0 +1,8 @@
+// Root entrypoint for OpenCode v2 directory-form plugin registration.
+//
+// v2 hosts (>= beta-18743) require config plugin entries to be directories
+// with an index entrypoint (`index.js`) and reject bare file paths
+// ("configured plugin path must be a directory"). npm/git package installs
+// resolve via package.json `main`; this file only serves the directory form
+// (e.g. `"plugin": ["~/superpowers"]` or a `node_modules/superpowers` path).
+export { default } from "./.opencode/plugins/superpowers.js";