Replace the worker's generic `"Continue."` default with a dispatch-time
`initialUserTurn` that is resolved per trigger. Message and peer-request
wakes now enumerate the actual unread messages (id, sender, channel,
subject, reply-to) so the agent's first user turn carries the entities
it is expected to act on, instead of idling into a status summary.
Drop the system-prompt `heartbeatFallbackSection`: its "respond with a
brief status summary" line fought the wake-reason block above it and
was the main reason communication wakes degraded into self-narration.
The wake-reason section plus the bound initial user turn now cover
every case that section was carrying.
ZacharyZhang-NY
271c6cfec8