.partial() silently drops .narrow() predicate (similar to #1468)

[yiidtw]

Similar to #1468 where spreading drops .narrow(), calling .partial() also silently drops it.

Reproduction

import { type } from "arktype";

const User = type({ name: "string", email: "string" })
  .narrow((u) => u.email.includes("@"));

User({ name: "Yi", email: "bad" });   // ✗ rejected (correct)

const PatchUser = User.partial();
PatchUser({ email: "bad" });           // ✓ accepted — narrow is gone

Expected

Should either preserve the narrow or throw if it can't. As a quick fix, throwing when .partial() is applied to a narrowed/filtered schema would at least make the issue visible — similar to how Zod handles .partial() on refined schemas.

Environment

• arktype 2.2.x
• Node 22

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