Cap and write-then-ack every inline delivery; codex via hooks only

Follow-up to #145, which fixed this for send only.

- router after-command delivery and listen use the shared InlineBatch: a
  chronological prefix capped at MAX_MESSAGES_PER_DELIVERY, written and
  flushed before a forward-only cursor advance; a failed write leaves the
  messages unread and fails the command
- '+N more unread' and late-arrival notices (stderr under --json)
- commands claim delivery (send once its message is persisted, listen when
  it takes a batch) so the router doesn't deliver twice; failed or
  early-returning commands still get router delivery
- router and send --from inline delivery is adhoc-only: codex has
  UserPromptSubmit/PostToolUse hooks, which the inline path pre-empted
- filter listen shows everything it acks, in event order (it dropped
  system messages and anything batched with the match), and reads past
  the cap, bounded to the initial backlog, for its match
- hook acks are forward-only and set name_announced in the same update