Set a typing indicator

Starts or stops a typing indicator shown to the recipient, as if someone were composing a message from your number. **iMessage numbers show it; standard (SMS) numbers ignore it.** SMS has no typing concept, so for a standard from-number the request succeeds and does nothing — the response is identical either way, letting you call this unconditionally before a send. The indicator is fire-and-forget: nothing is persisted and no event is emitted. Delivering a message or reaction from the same number **clears the indicator natively** on the recipient's device — platform behavior, not Dial's; start again after a send if you're still composing. Dial itself never clears it: send `value: false` when you stop composing without sending. (A stale indicator may also clear on its own device-side.) Free of charge.