Add per-autopilot member subscriber template that fans out to every
issue the autopilot spawns. New autopilot_subscriber table; extend
issue_subscriber.reason with 'autopilot' so the dispatch-time fanout
is distinguishable from manual subscriptions.
API: POST/PATCH /api/autopilots accept a `subscribers` array (member
user_type only for the first version); PATCH semantics are full-replace.
GET returns subscribers on the detail endpoint; the list endpoint omits
them to avoid an N+1.
Dispatch: dispatchCreateIssue lists the template inside the same tx as
the issue insert and writes the rows with reason='autopilot' before
EventIssueCreated fires, so notification listeners see the full
subscriber set on the first event.
Co-authored-by: multica-agent <github@multica.ai>
21e11ee511