chore: settle the public domain and move off port 3000

The application is published at horaires.ita-ito.com. One origin serves
both the panel and the browser, so the OIDC callback, the image URL the
device is handed and the documentation all follow from this single name.

Port 3000 is already taken by the facture_ocr stack on the development
machine, so the app listens on 3010 there and the reason is written next
to the setting rather than left to be rediscovered.

The fixtures and the frozen payload snapshot move to the real domain too:
a contract snapshot carrying a hostname that never existed is a small
puzzle left for whoever reads it next.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012cSY9pVhZmJUKNN7wf1Myd

scripts/preview.ts

@@ -61,7 +61,7 @@ function payload(): ScreenPayload {
     now: new Date('2026-09-23T10:30:00Z'),
     ctx: CONTEXT,
     shopName: 'ITA ITO',
-    logoUrl: 'https://trmnl.loxi.ch/brand/logo-eink.png',
+    logoUrl: 'https://horaires.ita-ito.com/brand/logo-eink.png',
     messages: [
       {
         textFr: 'Fermeture exceptionnelle jeudi matin',