When a series requires a pass and doesn't allow drop-ins, the
per-event availability endpoint returned a generic "No tickets
available" reason, leaving the UI to render an "Event Sold Out"
block for guests (logged-in users short-circuit via
check-series-access first).
Detect the gate server-side and return
{available:false, reason:"series_pass_required", requiresSeriesPass:true,
series:{id,title,slug}} so EventTicketPurchase's existing
requiresSeriesPass branch renders a pass-required CTA with a link to
the series page. The register and purchase handlers already enforce
the gate server-side; this is a messaging fix only.
Jennie Robinson Faber
8f0648de57