f.human: deliver the question to a channel (Slack / relay), not only the journal #468

#466 makes f.human(question, { to }) park the run on the kernel's wait.human and lets flows answer / Cloud's answer route (AgentWorkforce/cloud#3789) close it. to is recorded with the question (wait.human.requested_of) but never delivered: locally the question appears only in the exit-3 report and the journal; on Cloud only on the run record.

RFC-0001 covenant 3 says the ask must be delivered, not displayed: routed to the human's channels (Slack, WhatsApp, Telegram, iMessage) carrying the evidence, the exact question, and a one-tap answer, while the run parks durably.

Scope:

• Resolve to against declared tools (e.g. tools: { slack } → f.slack.dm(to, …) at park time, as a journaled helper effect under the root so a resume does not re-send).
• Carry the flows answer / Cloud answer invocation in the message; on Cloud, a one-tap answer means the channel callback hits POST /api/v1/workflows/runs/<id>/answer and then resumes.
• timeout on the wait (kernel never reads timeout_at_ms, DESIGN.md §1.4; EVENT-AWAIT.md §8 leans on resolving to false).

Non-goals here: changing the answer contract ({ answer, note?, answeredBy }, kernel-stamped at_ms, attribution: client_asserted).

Raised by review on #466 (thread 4046811231).