Move webmention parsing and authorship into the app

The jonnybarnes/webmentions-parser package is now archived, and its
guzzlehttp/guzzle ^6|^7 constraint was the only thing holding Guzzle
back from 8. Port the parts we use into App\Services\WebMention and
drop the package.

Parser keeps getMentionType and the checkInReplyTo/LikeOf/RepostOf
checks unchanged. Authorship follows the same authorship algorithm,
with some fixes:

- fetch the author page with Laravel's Http client, so tests can fake
  it, and treat connection failures as AuthorshipParserException too
- keep state in locals so one instance can be reused safely
- make the url == uid == author-page check actually compare the
  h-card's uid, rather than an undefined variable

Add direct tests for both, and mark the library as archived on the
projects page.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Unit/Jobs/ProcessWebMentionJobTest.php

@@ -10,11 +10,11 @@ use App\Jobs\ProcessWebMention;
 use App\Jobs\SaveProfileImage;
 use App\Models\Note;
 use App\Models\WebMention;
+use App\Services\WebMention\Parser;
 use Illuminate\FileSystem\FileSystem;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 use Illuminate\Support\Facades\Http;
 use Illuminate\Support\Facades\Queue;
-use Jonnybarnes\WebmentionsParser\Parser;
 use PHPUnit\Framework\Attributes\Test;
 use Tests\TestCase;