release workflow: publish multi-arch images; settings: confirm language switch

- release.yml: add QEMU + platforms: linux/amd64,linux/arm64 to both
  build-push steps so the published images work on Apple Silicon (fixes
  'no matching manifest for linux/arm64/v8' on docker compose pull).
- Settings -> Profile language picker is now a select that opens a
  confirmation dialog before applying, instead of switching instantly.
- CLAUDE.md: require a dated docs changelog entry for every release.

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

frontend/lib/i18n/locales/en/translation.json

@@ -1689,7 +1689,11 @@
         "description": "The language temetro's interface is shown in on this device.",
         "label": "Display language",
         "en": "English",
-        "fr": "Français"
+        "fr": "Français",
+        "confirmTitle": "Change display language?",
+        "confirmBody": "Switch the interface to {{language}}? The app will reload its text in the new language.",
+        "confirmCta": "Change language",
+        "cancel": "Cancel"
       },
       "patientNotifications": "Patient notifications",
       "patientNotificationsDescription": "Emails sent to patients about their records, results, and pending approvals",

frontend/lib/i18n/locales/fr/translation.json

@@ -1689,7 +1689,11 @@
         "description": "La langue dans laquelle l'interface de temetro s'affiche sur cet appareil.",
         "label": "Langue d'affichage",
         "en": "English",
-        "fr": "Français"
+        "fr": "Français",
+        "confirmTitle": "Changer la langue d'affichage ?",
+        "confirmBody": "Basculer l'interface en {{language}} ? L'application rechargera ses textes dans la nouvelle langue.",
+        "confirmCta": "Changer la langue",
+        "cancel": "Annuler"
       },
       "patientNotifications": "Notifications patients",
       "patientNotificationsDescription": "E-mails envoyés aux patients à propos de leurs dossiers, résultats et approbations en attente",