Deprecate pasted-text fallback in `useInput` and make `usePaste` the only paste API

Probably not soon, but at some point.

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Summary

useInput currently still receives pasted text when no usePaste listener is active. This is legacy behavior and makes input semantics inconsistent.

Proposal

• Deprecate pasted-text delivery via useInput in the current major.
• In the next major, stop forwarding bracketed paste payloads to useInput.
• Keep usePaste as the dedicated API for paste blobs.

Why

• Clearer API boundaries: key events (useInput) vs paste blobs (usePaste).
• Simpler handlers: no mixed key/paste assumptions in one callback.
• More predictable behavior across terminals.

Migration

If your app relies on pasted text in useInput, switch to usePaste for paste handling and keep useInput for typed key events.