feat: ticketing sync workers with idempotent import and orphan flagging (phase 6)

- task domain model + exhaustive §4.4 status machine tests (single source of truth)
- per-customer polling workers reconciled every 30s from the customers
  collection; panic-safe runs; manual sync-now trigger; status provider
  for the admin panel
- §5.3 upsert keyed on (system, key, customerId): refreshes content while
  status=imported, records upstream_changed timeline + notification after
- attachments cached into GridFS via connector-authorized downloads
- orphaned tickets flagged with timeline + consultant notification, never
  deleted; idempotent across polls
- consultant identity from users.extra.ticketingIdentities per system
- notifications store (insert/list/unread-count/mark-read)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

internal/http/providers.go

@@ -22,6 +22,19 @@ func (s *Server) SetPerformerInfo(b BreakerInfo) { s.performer = b }
 
 // SetSyncTrigger wires the sync manager's "sync now" entry point.
 func (s *Server) SetSyncTrigger(f func(customerID string)) { s.syncTrigger = f }
+
+// Publish forwards a live event to connected clients. Until the WebSocket
+// hub lands this is a metrics-only no-op, so subsystems can emit events
+// unconditionally.
+func (s *Server) Publish(channel, event string, payload any) {
+	s.metrics.Inc("events_published_total", 1)
+	if s.publishFn != nil {
+		s.publishFn(channel, event, payload)
+	}
+}
+
+// SetPublishFn wires the actual hub broadcast.
+func (s *Server) SetPublishFn(f func(channel, event string, payload any)) { s.publishFn = f }
 func (s *Server) SetSyncStatusProvider(p StatusProvider) {
 	s.syncProvider = p
 }