✨ 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/database/migrations/2026_02_07_000001_create_narrator_texts_table.php

@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('narrator_texts', function (Blueprint $table) {
+            $table->id();
+            $table->string('context');
+            $table->string('text_key');
+            $table->integer('variant')->default(1);
+            $table->enum('hero_type', ['recruteur', 'client', 'dev'])->nullable();
+            $table->timestamps();
+
+            $table->index('context');
+            $table->index(['context', 'hero_type']);
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('narrator_texts');
+    }
+};