feat(rebrand): align jobTitle + meta + i18n on Hytale Plugin Developer (REBRAND-01/02/03)

- app/pages/index.vue: JSON-LD utilise siteConfig.jobTitle (Hytale Plugin Developer)
  + siteConfig.contact.email au lieu de hardcode "Developpeur Full Stack"
- nuxt.config.ts: site.name "Developpeur Full Stack" → "Hytale Plugin Developer"
- app/data/site.ts: description "Professional Full Stack Developer..." →
  "Hytale Plugin Developer & Web Developer..."
- i18n/fr.json + en.json: refonte positionnement sur 14 clés
  - a11y.logoLabel, seo.home/about/contact, about.title/intro/approach/cta,
    home.cta2, contact.title/subtitle/faq.projectTypes, projects.subtitle
  - Le titre principal "Hytale Plugin Developer & [Freelance] Web Dev"
  - Les 2 occurrences "full stack" restantes sont contextuelles (skills)

Laisse les projets web/bot existants (virtual-tour, flowboard, xinko...) visibles,
mentionne Hytale plugins car Phase 10 (5 démos) est planifiée.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/data/site.ts

@@ -6,7 +6,7 @@ export const siteConfig: SiteConfig = {
   name: 'Killian',
   title: "Killian' DAL-CIN - Hytale Plugin Developer | Freelance",
   description:
-    'Professional Full Stack Developer specializing in modern web development with Vue.js, React, Node.js. Expert in Discord bots, web applications, and custom software solutions.',
+    'Hytale Plugin Developer & Web Developer. Custom Java plugins for Hytale servers, gaming websites, Discord bots, and full-stack web applications.',
   jobTitle: 'Hytale Plugin Developer',
   author: 'Killian',
   url: 'https://killiandalcin.fr',