feat: Publication de pages — notes publiques sur URL

- Migration: champs isPublic + publicSlug + publishedAt sur Note
- Route publique /p/[slug] — rendu SSR sans auth, prose styled
- Server actions: publishNote / unpublishNote / getPublishedNote
- API /api/notes/publish — toggle publication + génération slug
- PublishDialog — modal avec lien copiable + bouton dépublier
- Bouton Globe dans le toolbar (vert si publiée)
- i18n FR/EN
- Pattern inspiré de BrainstormSession.isPublic

memento-note/locales/en.json

@@ -2563,6 +2563,13 @@
     "slashAiWriter": "Write with AI",
     "slashAiWriterDesc": "Generate content at cursor",
     "aiWriterPlaceholder": "Describe what you want to write...",
+    "publishTitle": "Public publishing",
+    "publishDesc": "Publish this note on a public URL. Anyone with the link can read it.",
+    "publish": "Publish",
+    "publishSuccess": "Note published!",
+    "publishLive": "Live",
+    "unpublish": "Unpublish",
+    "unpublishSuccess": "Note unpublished",
     "slashSubPage": "Sub-page",
     "slashSubPageDesc": "Create a linked note inside this note",
     "exercisesLoading": "Generating exercises...",