feat(brand): swap recipient-facing pictureFrame strings to WeVisto

Updated: SPA <title>, PWA manifest name/short_name, iOS web-app title,
"Install"/"Pin to home screen" copy, HomeView empty state, all Twig page
titles (login/register/setup/token/help), and the share-notification
email header. Left alone: the firmware-broadcast SSID PictureFrame-XXXX
(coordinated firmware change needed) and internal code/comment refs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

templates/emails/share_notification.txt.twig

@@ -1,4 +1,4 @@
-{{ sharer.email }} shared a photo with you on pictureFrame.
+{{ sharer.email }} shared a photo with you on WeVisto.
 
 Add to my frame:
 {{ absolute_url('/token/' ~ approveToken.uuid ~ '/approve') }}