✨ Add skills page with category grouping (Story 2.4)

- Enhance Skill model with getCurrentLevel() and ordered scope
- Update SkillController to group by category with translated labels
- Add level and project_count to SkillResource
- Create skill.ts types (Skill, SkillCategory, SkillsResponse)
- Create useFetchSkills composable
- Create SkillCard component with animated progress bar
- Implement competences.vue with:
  - Responsive grid (2/3/4 columns)
  - Category sections with icons
  - Stagger animations (respects prefers-reduced-motion)
  - Loading/error/empty states
  - Placeholder for vis.js skill tree (Epic 3)

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

api/app/Models/Skill.php

@@ -34,6 +34,13 @@ class Skill extends Model
 
     public function scopeOrdered(Builder $query): Builder
     {
-        return $query->orderBy('display_order');
+        return $query->orderBy('category')->orderBy('display_order');
+    }
+
+    public function getCurrentLevel(): int
+    {
+        $maxLevelAfter = $this->projects()->max('skill_project.level_after');
+
+        return $maxLevelAfter ?? 1;
     }
 }