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.vue

@@ -271,23 +271,7 @@
                           >
                             <span
                               style="white-space: normal; line-height: 1.3"
-                              v-text="
-                                `${wave.title} - ${wave.opening_date} to ${
-                                  wave.closing_date
-                                } - ${
-                                  isFiatCurrency(wave.currency)
-                                    ? LNbits.utils.formatCurrency(
-                                        Number(
-                                          wave.price_per_ticket || 0
-                                        ).toFixed(2),
-                                        wave.currency
-                                      )
-                                    : `${wave.price_per_ticket} sats`
-                                } - ${wave.amount_tickets} tickets - ${soldTicketsForWave(
-                                  props.row.id,
-                                  wave.id
-                                )} sold`
-                              "
+                              v-text="waveSummary(props.row.id, wave)"
                             ></span>
                           </q-chip>
                         </div>