🗃️ Add database schema, models & seeders (Story 1.2)

Migrations (translations, projects, skills, skill_project), Eloquent models
with belongsToMany relations, scopes, and test seeders (74 translations FR/EN,
10 skills, 3 projects, 12 skill-project links).

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

api/app/Models/Project.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+
+class Project extends Model
+{
+    protected $fillable = [
+        'slug',
+        'title_key',
+        'description_key',
+        'short_description_key',
+        'image',
+        'url',
+        'github_url',
+        'date_completed',
+        'is_featured',
+        'display_order',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'date_completed' => 'date',
+            'is_featured' => 'boolean',
+        ];
+    }
+
+    public function skills(): BelongsToMany
+    {
+        return $this->belongsToMany(Skill::class, 'skill_project')
+            ->withPivot(['level_before', 'level_after', 'level_description_key'])
+            ->withTimestamps();
+    }
+
+    public function scopeFeatured(Builder $query): Builder
+    {
+        return $query->where('is_featured', true);
+    }
+
+    public function scopeOrdered(Builder $query): Builder
+    {
+        return $query->orderBy('display_order');
+    }
+}