Review finding on #114941: the CLI-runner branch of `_spawn_delivery` still
answered `status: sent` with only a `process_id`, while the live-owner branch
answers `queued`/`claimed` + `delivery_id` and the relay branch `queued`. One
tool, three vocabularies; `sent` also reads as a delivery receipt, which is the
misreading this PR exists to remove.
`_spawn_delivery` now returns `status: queued`, a `delivery_id` and the
`process_id`. For CLI-runner deliveries the id is the same sha256 of the DM
file path the runner pins when it admits to a live owner (`_dm_delivery_id`,
replacing three inline copies), so the ack and any live receipt correlate; the
relay branch passes the envelope id (also on its notification_error ack).
`sent_at` becomes `queued_at`. Tool schema, Bot Mode user guide and the
assertions in tests/tools follow; two invariant tests pin the CLI-runner and
relay ids (red before, green after).
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