Initial commit: Laravel scaffold + Common Crawl site indexing

Adds Site/SitePage models and the crawlindex:fetch command, which pulls
CDX index records from Common Crawl and optionally enriches them with
page title/description/keywords/body text extracted from the WARC
archive. CDX/WARC access and the site/page upsert logic live in
CommonCrawlIndexService and WarcRecordFetcher.

bootstrap/providers.php

@@ -0,0 +1,7 @@
+<?php
+
+use App\Providers\AppServiceProvider;
+
+return [
+    AppServiceProvider::class,
+];