feat: Link Preview block (carte aperçu URL) + proxy images

- Bloc Link Preview : colle une URL → carte avec titre, description, image, favicon
- API /api/link-preview : extraction OpenGraph + meta tags
- API /api/image-proxy : contourne le hotlinking (Referer spoofing)
- Métadonnées persistées en HTML (data-preview JSON) — pas de refetch au reload
- Texte indexable : titre + description + URL inclus pour recherche/embeddings
- Modal propre pour saisir l'URL (plus de prompt())
- Slash menu + smart paste 'Coller comme carte aperçu'
- i18n FR/EN complet
- Fix: bouton calendrier retiré du sélecteur de vue

memento-note/locales/en.json

@@ -2427,6 +2427,14 @@
     "findWholeWord": "Whole word",
     "findRegex": "Regular expression",
     "findReplaceToggle": "Show/Hide replace",
+    "slashLinkPreview": "Link Preview",
+    "slashLinkPreviewDesc": "Turn a URL into a visual card",
+    "linkPreviewLoading": "Loading preview...",
+    "linkPreviewModalTitle": "Paste a link",
+    "linkPreviewModalInsert": "Create preview",
+    "linkPreviewUnwrap": "Revert to simple link",
+    "linkPreviewDelete": "Delete preview",
+    "smartPasteUrlPreview": "Paste as preview card",
     "calloutDelete": "Delete callout",
     "calloutUnwrap": "Disable callout",
     "calloutInfo": "Information",
@@ -2611,6 +2619,8 @@
     "viewKanban": "Kanban",
     "viewGallery": "Gallery",
     "viewKanbanHint": "Columns — like Trello to track your notes",
+    "viewCalendarHint": "Calendar — your notes organized by date",
+    "calendarNoDateProperty": "Add a date property to use the calendar view",
     "viewGalleryHint": "Visual cards — browse your notes at a glance",
     "intro": {
       "databaseTitle": "Organized notebook",