fix(ui): voix Second Brain à la connexion et libellés du rail

Remplace le titre « notepad » et le jargon (Intelligence OS, SM-2) par des mots lisibles, et aligne la langue des pages d’auth sur le reste du site.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/locales/en.json

@@ -32,10 +32,10 @@
     "signOut": "Sign out",
     "confirmPassword": "Confirm Password",
     "confirmPasswordPlaceholder": "Confirm your password",
-    "welcomeBack": "Welcome Back",
-    "welcomeBackSubtitle": "Enter your credentials to access your notes.",
-    "createYourSpace": "Create Your Space",
-    "createYourSpaceSubtitle": "Join the new era of smart note-taking.",
+    "welcomeBack": "Welcome back",
+    "welcomeBackSubtitle": "Sign in to find your notes, your connections, and what you forgot.",
+    "createYourSpace": "Create your second brain",
+    "createYourSpaceSubtitle": "It connects while you write — not just another notes app.",
     "forgot": "Forgot?",
     "backToSite": "Back to site",
     "privacyTerms": "© 2025 Memento Labs — Privacy · Terms",
@@ -97,8 +97,8 @@
     "dashboardPanelBody": "Your second brain at a glance: AI suggestions, quick capture, and next steps. Use the shortcuts below to jump into action.",
     "searchNotebooksPlaceholder": "Search notebooks…",
     "clearSearch": "Clear search",
-    "insightsPanelBody": "Semantic map of your notes: thematic clusters, bridge notes, and connection suggestions.",
-    "revisionPanelBody": "Review flashcards with the SM-2 algorithm. Decks are generated from your notes.",
+    "insightsPanelBody": "A map of how your notes connect: related themes, bridge notes, and links you can open.",
+    "revisionPanelBody": "Review with flashcards. Spaced repetition brings them back at the right time. Packs come from your notes.",
     "backToNotebooks": "Back to notebooks",
     "resizeNotebooksPanel": "Resize notebooks panel",
     "resizeSidebar": "Resize sidebar width",
@@ -1001,7 +1001,7 @@
   "nav": {
     "home": "Home",
     "notes": "Notes",
-    "notebooks": "NOTEBOOKS",
+    "notebooks": "Notebooks",
     "generalNotes": "General Notes",
     "archive": "Archive",
     "settings": "Settings",
@@ -1015,7 +1015,7 @@
     "support": "Support Memento ☕",
     "reminders": "Reminders",
     "graphView": "Link map",
-    "insights": "Semantic themes",
+    "insights": "Connections",
     "revision": "Review",
     "dailyNotes": "Daily Notes",
     "dashboard": "Dashboard",
@@ -2542,7 +2542,7 @@
         "slideStyle": "Visual style affects corner radius, spacing, and information density."
       }
     },
-    "intelligenceOS": "Intelligence OS"
+    "intelligenceOS": "Agents"
   },
   "chat": {
     "title": "AI Chat",