feat(events): pipe displayTimezone through list and sidebar formatters

Sidebar (EventsMiniSidebar), public events list, member dashboard
"Upcoming" block, and EventTicketPurchase all formatted dates in
viewer-local TZ. Switch each formatter to accept the event (or an
eventTimezone prop) and pass it to Intl.DateTimeFormat so the
displayed wall-clock matches the event's intended zone.

app/components/EventTicketPurchase.vue

@@ -231,6 +231,10 @@ const props = defineProps({
     type: String,
     required: true,
   },
+  eventTimezone: {
+    type: String,
+    default: "America/Toronto",
+  },
   userEmail: {
     type: String,
     default: null,
@@ -415,6 +419,7 @@ const formatEventDate = (date) => {
     month: "long",
     day: "numeric",
     year: "numeric",
+    timeZone: props.eventTimezone || "America/Toronto",
   });
 };
 </script>