Day-parting flows: shutdown dispatch queue and morning briefing #410

From the practitioner-workflow research: the strongest cross-source daily ritual is temporal — end-of-day dispatch, overnight execution, morning review. Ship it as a product primitive: (1) a 'Shutdown dispatch' flow that queues tonight's threads in the last 30 minutes of the day; (2) a 'Morning briefing' surface with overnight results pre-digested, review-first (pairs with #323's morning digest); (3) a report-only scout permission preset (read + report, never comment/PR — Hashimoto's triage agents) for the overnight triage runs feeding it.