✨ Add testimonials page with personality-styled cards (Story 2.6)

- Add testimonials table migration with personality enum
- Create Testimonial model with HasTranslations trait
- Add TestimonialSeeder with 4 test testimonials
- Create TestimonialController and TestimonialResource
- Add useFetchTestimonials composable
- Create TestimonialCard component with personality-based styling
- Add temoignages.vue page with loading/error states
- Add testimonials translations in FR/EN

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

frontend/i18n/en.json

@@ -108,6 +108,15 @@
     "load_projects_error": "Unable to load related projects",
     "no_related_projects": "No projects use this skill yet"
   },
+  "testimonials": {
+    "page_title": "Testimonials | Skycel",
+    "page_description": "Discover what my collaborators and clients say about my work.",
+    "load_error": "Unable to load testimonials...",
+    "no_testimonials": "No testimonials yet",
+    "cta_title": "Want to work together?",
+    "cta_description": "Let's discuss your project and see how I can help.",
+    "cta_button": "Contact me"
+  },
   "pages": {
     "projects": {
       "title": "Projects",