✨ Add narrator texts infrastructure with API (Story 3.1)

- Create narrator_texts table migration with context/hero_type indexes
- Add NarratorText model with getRandomText() for variant selection
- Add NarratorTextSeeder with 30+ texts for 11 contexts
- Implement vouvoiement (recruteur) vs tutoiement (client/dev)
- Create NarratorController with GET /api/narrator/{context}
- Add useFetchNarratorText composable for frontend

Contexts: intro, transitions, hints, encouragements, contact_unlocked, welcome_back

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

api/app/Models/NarratorText.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+
+class NarratorText extends Model
+{
+    protected $fillable = [
+        'context',
+        'text_key',
+        'variant',
+        'hero_type',
+    ];
+
+    public function scopeForContext(Builder $query, string $context): Builder
+    {
+        return $query->where('context', $context);
+    }
+
+    public function scopeForHero(Builder $query, ?string $heroType): Builder
+    {
+        if ($heroType) {
+            return $query->where(function ($q) use ($heroType) {
+                $q->where('hero_type', $heroType)
+                  ->orWhereNull('hero_type');
+            });
+        }
+
+        return $query->whereNull('hero_type');
+    }
+
+    public static function getRandomText(string $context, ?string $heroType = null): ?self
+    {
+        $query = static::forContext($context);
+
+        if ($heroType) {
+            // Priorité aux textes spécifiques au héros, sinon textes génériques
+            $heroSpecific = (clone $query)->where('hero_type', $heroType)->inRandomOrder()->first();
+            if ($heroSpecific) {
+                return $heroSpecific;
+            }
+        }
+
+        return $query->whereNull('hero_type')->inRandomOrder()->first();
+    }
+}