✨ Add layouts, routing, transitions & pages (Story 1.4)

Default layout with sticky AppHeader (nav, LanguageSwitcher, mobile hamburger),
AppFooter with social links. Minimal layout for express mode. 7 placeholder pages
with localized EN routes. Page transitions (fade+slide), prefers-reduced-motion
support, custom scroll behavior, error.vue, useSeo composable, SVG favicon.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/i18n/en.json

@@ -14,7 +14,9 @@
     "discover": "Discover",
     "close": "Close",
     "loading": "Loading...",
-    "language": "Language"
+    "language": "Language",
+    "back_home": "Back to home",
+    "back_to_adventure": "Back to the adventure"
   },
   "landing": {
     "title": "Welcome to my universe",
@@ -23,8 +25,8 @@
     "cta_express": "Express mode"
   },
   "error": {
-    "404": "Page not found",
-    "generic": "An error occurred"
+    "404": "Oops! This page seems to have gotten lost in the code...",
+    "generic": "An unexpected error occurred. The Bug is investigating..."
   },
   "meta": {
     "title": "Skycel - Célian's Portfolio",
@@ -33,5 +35,31 @@
   "footer": {
     "copyright": "© {year} Célian — Skycel",
     "built_with": "Built with Nuxt & Laravel"
+  },
+  "pages": {
+    "projects": {
+      "title": "Projects",
+      "description": "Discover my projects and achievements"
+    },
+    "skills": {
+      "title": "Skills",
+      "description": "My technical and soft skills"
+    },
+    "testimonials": {
+      "title": "Testimonials",
+      "description": "What people say about my work"
+    },
+    "journey": {
+      "title": "Journey",
+      "description": "My professional and personal journey"
+    },
+    "contact": {
+      "title": "Contact",
+      "description": "Get in touch with me"
+    },
+    "resume": {
+      "title": "Quick Resume",
+      "description": "The essentials at a glance"
+    }
   }
 }