Fix gallery images blocked by OpaqueResponseBlocking

Try same-origin (/photos, /uploads via main nginx) before falling back
to photobackend subdomain, which returns 502 for static files.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

main-site/gallery/gallery.js

@@ -80,6 +80,7 @@ document.addEventListener('DOMContentLoaded', () => {
     const apiBaseCandidates = (() => {
         const hints = [
             window.GALLERY_API_URL || '',
+            window.location.origin,
             'https://photobackend.beachpartyballoons.com',
         ];
         return [...new Set(hints.filter(Boolean))];