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

resources/lang/en/comments.php

@@ -0,0 +1,9 @@
+<?php
+
+return [
+    'deleted_comment' => 'This comment was deleted.',
+    'edited' => 'edited',
+    'load_more' => 'Load more comments',
+    'no_comments' => 'No comments yet.',
+    'comment_placeholder' => 'Write a comment...',
+];