🎉 Init monorepo Nuxt 4 + Laravel 12 (Story 1.1)

Setup complet de l'infrastructure projet :
- Frontend Nuxt 4 (SSR, TypeScript, i18n, Pinia, TailwindCSS)
- Backend Laravel 12 API-only avec middleware X-API-Key et CORS
- Design tokens (sky-dark, sky-accent, sky-text) et polices (Merriweather, Inter)
- Documentation planning et implementation artifacts

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

api/.gitattributes

@@ -0,0 +1,11 @@
+* text=auto eol=lf
+
+*.blade.php diff=html
+*.css diff=css
+*.html diff=html
+*.md diff=markdown
+*.php diff=php
+
+/.github export-ignore
+CHANGELOG.md export-ignore
+.styleci.yml export-ignore