Migration to Zod v4 #10
Description
As convex-helpers 0.1.105 has already supported zod v4 in get-convex/convex-helpers@aa25efe, it would be great that we could also bump zod and migrate related code snippets in the template.
Related PR get-convex/convex-helpers#840 and code examples get-convex/convex-helpers#851.