feat: Implement read cursor activity tracking and recent activity dashboard with context

app/Models/ReadCursor.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
+
+class ReadCursor extends Model
+{
+    protected $fillable = [
+        'user_id',
+        'cursorable_id',
+        'cursorable_type',
+        'read_at',
+    ];
+
+    protected $casts = [
+        'read_at' => 'datetime',
+    ];
+
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class);
+    }
+
+    public function cursorable(): MorphTo
+    {
+        return $this->morphTo();
+    }
+}

app/Models/User.php

@@ -44,6 +44,11 @@ class User extends Authenticatable implements PasskeyUser
         return $this->hasMany(Mutation::class);
     }
 
+    public function readCursors()
+    {
+        return $this->hasMany(ReadCursor::class);
+    }
+
     /**
      * Get the attributes that should be cast.
      *