fix: remove redundant Required<> from input and output type definitions (#5033)

The Required<> utility type was redundant in both input and output type definitions because the type guards already ensure these are required properties. If they were optional, the conditions would fail and return 'unknown'. This redundant mapped type caused TS2615 circular reference errors in TypeScript 5.9+. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-authored-by: Claude <noreply@anthropic.com>

Author: yz89122

packages/zod/src/v4/core/core.ts

@@ -84,8 +84,8 @@ export class $ZodAsyncError extends Error {
 // export type output<T extends schemas.$ZodType> = T["_zod"]["output"];
 // export type input<T extends schemas.$ZodType> = T["_zod"]["input"];
 // export type output<T extends schemas.$ZodType> = T["_zod"]["output"];
-export type input<T> = T extends { _zod: { input: any } } ? Required<T["_zod"]>["input"] : unknown;
-export type output<T> = T extends { _zod: { output: any } } ? Required<T["_zod"]>["output"] : unknown;
+export type input<T> = T extends { _zod: { input: any } } ? T["_zod"]["input"] : unknown;
+export type output<T> = T extends { _zod: { output: any } } ? T["_zod"]["output"] : unknown;
 
 // Mk2
 // export type input<T> = T extends { _zod: { "~input": any } }