Expand IGDB data: collections, game modes, themes, perspectives, videos, websites, age ratings, similar games; add backfill command

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

database/migrations/2026_06_01_000001_create_collections_table.php

@@ -0,0 +1,16 @@
+<?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('collections', function (Blueprint $table) {
+            $table->id();
+            $table->unsignedInteger('igdb_id')->unique();
+            $table->string('name');
+            $table->string('slug')->nullable();
+            $table->timestamps();
+        });
+    }
+    public function down(): void { Schema::dropIfExists('collections'); }
+};