feat: initial release of relaticle/comments

Filament comments package with:
- Polymorphic commenting on any Eloquent model
- Threaded replies with configurable depth
- @mentions with autocomplete and user search
- Emoji reactions with toggle and who-reacted tooltips
- File attachments via Livewire uploads
- Reply and mention notifications via Filament notification system
- Thread subscriptions for notification control
- Real-time broadcasting (opt-in Echo) with polling fallback
- Dark mode support
- CommentsAction, CommentsTableAction, CommentsEntry for Filament integration
- 204 tests, 421 assertions

src/Notifications/UserMentionedNotification.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Relaticle\Comments\Notifications;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Notification;
+use Illuminate\Support\Str;
+use Relaticle\Comments\Comment;
+use Relaticle\Comments\Config;
+
+class UserMentionedNotification extends Notification
+{
+    public function __construct(
+        public readonly Comment $comment,
+        public readonly Model $mentionedBy,
+    ) {}
+
+    /** @return array<int, string> */
+    public function via(mixed $notifiable): array
+    {
+        return Config::getNotificationChannels();
+    }
+
+    /** @return array<string, mixed> */
+    public function toDatabase(mixed $notifiable): array
+    {
+        return [
+            'comment_id' => $this->comment->id,
+            'commentable_type' => $this->comment->commentable_type,
+            'commentable_id' => $this->comment->commentable_id,
+            'mentioner_name' => $this->mentionedBy->getCommentName(),
+            'body' => Str::limit(strip_tags($this->comment->body), 100),
+        ];
+    }
+
+    public function toMail(mixed $notifiable): MailMessage
+    {
+        $mentionerName = $this->mentionedBy->getCommentName();
+
+        return (new MailMessage)
+            ->subject('You were mentioned in a comment')
+            ->line("{$mentionerName} mentioned you in a comment:")
+            ->line(Str::limit(strip_tags($this->comment->body), 200));
+    }
+}