feat: add community activity feed and mentions

app/Models/UserMention.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class UserMention extends Model
+{
+    protected $table = 'user_mentions';
+
+    public $timestamps = false;
+
+    protected $fillable = [
+        'user_id',
+        'mentioned_user_id',
+        'artwork_id',
+        'comment_id',
+        'created_at',
+    ];
+
+    protected $casts = [
+        'user_id' => 'integer',
+        'mentioned_user_id' => 'integer',
+        'artwork_id' => 'integer',
+        'comment_id' => 'integer',
+        'created_at' => 'datetime',
+    ];
+
+    public function actor(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'user_id');
+    }
+
+    public function mentionedUser(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'mentioned_user_id');
+    }
+
+    public function artwork(): BelongsTo
+    {
+        return $this->belongsTo(Artwork::class);
+    }
+
+    public function comment(): BelongsTo
+    {
+        return $this->belongsTo(ArtworkComment::class, 'comment_id');
+    }
+}