fix(events): show the venue-local concert time consistently

Backend sent the UTC `dateTime` (a 20:00 local show read as 08:00Z), and
Android's ZonedDateTime.parse choked on zone-less values → some rows had a
wrong time, others none at all.

- Backend: prefer localDate+localTime (venue-local, naive) over the UTC instant.
- Android: parse a naive LocalDateTime first, fall back to ZonedDateTime for
  older "…Z" values. Web already renders the naive string as-is.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/novasonic-server.js

@@ -393,9 +393,12 @@ app.get('/api/events/:artist', (req, res) => {
         const events = raw.map(e => {
           const venue   = e._embedded?.venues?.[0] || {};
           const start   = e.dates?.start || {};
-          const dt      = start.dateTime || (start.localDate
+          // Prefer the venue-LOCAL date/time (localDate + localTime) over the UTC `dateTime` —
+          // otherwise a 20:00 local show is shown as its 08:00Z UTC instant. Sent as a naive local
+          // datetime string (no zone); the clients render it as-is.
+          const dt      = (start.localDate
             ? `${start.localDate}T${start.localTime || '00:00:00'}`
-            : null);
+            : start.dateTime) || null;
           const soldOut = e.dates?.status?.code === 'offsale' ||
                           e.dates?.status?.code === 'cancelled';
           return {