Add missing files and fix type aliases for opentui features

packages/opencode/src/util/fn.ts

@@ -0,0 +1,11 @@
+import { z } from "zod"
+
+export function fn<T extends z.ZodType, Result>(schema: T, cb: (input: z.infer<T>) => Result) {
+  const result = (input: z.infer<T>) => {
+    const parsed = schema.parse(input)
+    return cb(parsed)
+  }
+  result.force = (input: z.infer<T>) => cb(input)
+  result.schema = schema
+  return result
+}