✨ Add journey timeline page with scroll animations (Story 2.8)

- Create useIntersectionObserver composable for scroll-triggered animations
- Add TimelineItem component with alternating layout (desktop)
- Implement journey page with i18n-based milestones data
- Add 7 career milestones (2018-2025) in FR and EN
- Gradient timeline line with animated connection points
- Glassmorphism card design with hover effects
- Respect prefers-reduced-motion for all animations

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

docs/implementation-artifacts/sprint-status.yaml

@@ -64,7 +64,7 @@ development_status:
   2-5-competences-cliquables-projets-lies: review
   2-6-page-temoignages-migrations-bdd: review
   2-7-composant-dialogue-pnj: review
-  2-8-page-parcours-timeline-narrative: ready-for-dev
+  2-8-page-parcours-timeline-narrative: review
   epic-2-retrospective: optional
 
   # ═══════════════════════════════════════════════════════════════════════════