fix(ui): ticket waves never rendered in the organiser table

The expanded event row showed "Ticket waves" with a + button and an
empty list, however many waves the event had. Reported from aio-demo and
reproduced in a fresh incognito window, so not a caching artifact.

The chip built its label inline with `LNbits.utils.formatCurrency(...)`.
Vue resolves template expressions against the component instance, where
the `LNbits` global is not in scope, so the expression threw

    TypeError: Cannot read properties of undefined (reading 'utils')

and the whole v-for rendered nothing. The promo-code chips beside it
were unaffected, which is what made the list look like a data problem —
the waves were always present in the response.

That line arrived with the v1.6.8 merge: it is upstream's, and upstream
is the only `LNbits.` reference in any template in this extension
(display.vue and ticket.vue have none). So the convention here was
already "format in a method", and the merge quietly broke it.

`waveSummary` now builds the label in index.js, where the global is in
scope. It also trims the day off wave dates for display — closing_date
defaults from event_end_date and can carry a time, which was rendering
as "2026-12-09T16:00:00+01:00" in the chip.

Verified in a browser against a two-wave event: both chips render as
"Primary wave - 2026-10-03 to 2026-11-02 - €30.00 - 50 tickets - 0 sold"
with no TypeError.

static/js/index.js

@@ -414,6 +414,26 @@ window.PageEvents = {
         this.ticketImageUploadTarget = null
       }
     },
+    waveSummary(eventId, wave) {
+      // Built here, not in the template. Vue resolves template expressions
+      // against the component instance, where the `LNbits` global is NOT
+      // in scope — upstream's v1.6.8 chip called `LNbits.utils` inline and
+      // threw "Cannot read properties of undefined (reading 'utils')",
+      // which killed the whole v-for and left the wave list looking empty.
+      // No other template in this extension touches `LNbits` directly.
+      const price = this.isFiatCurrency(wave.currency)
+        ? LNbits.utils.formatCurrency(
+            Number(wave.price_per_ticket || 0).toFixed(2),
+            wave.currency
+          )
+        : `${wave.price_per_ticket} sats`
+      // Wave dates can carry a time (closing_date defaults from
+      // event_end_date); show the day only.
+      const opens = String(wave.opening_date || '').slice(0, 10)
+      const closes = String(wave.closing_date || '').slice(0, 10)
+      const sold = this.soldTicketsForWave(eventId, wave.id)
+      return `${wave.title} - ${opens} to ${closes} - ${price} - ${wave.amount_tickets} tickets - ${sold} sold`
+    },
     soldTicketsForWave(eventId, waveId) {
       return this.allPaidTickets.filter(
         ticket =>