Implement file upload and viewing functionality; refactor letter migrations and models to use UUIDs

app/Models/User.php

@@ -6,6 +6,7 @@ namespace App\Models;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Foundation\Auth\User as Authenticatable;
 use Illuminate\Notifications\Notifiable;
+use Illuminate\Support\Str;
 use Laravel\Sanctum\HasApiTokens;
 
 class User extends Authenticatable
@@ -46,4 +47,15 @@ class User extends Authenticatable
             'password' => 'hashed',
         ];
     }
+
+    protected $keyType = 'string';
+    public $incrementing = false;
+
+    public static function boot() {
+        parent::boot();
+
+        static::creating(function ($model) {
+            $model->id = Str::uuid();
+        });
+    }
 }