feat: add app and database modules

app/Exceptions/BackupOperationException.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Exceptions;
+
+use RuntimeException;
+
+class BackupOperationException extends RuntimeException
+{
+    public static function missingBinary(string $binary): self
+    {
+        return new self("Required binary '{$binary}' is not installed on the server.");
+    }
+
+    public static function diskNotConfigured(string $disk): self
+    {
+        return new self("Backup disk '{$disk}' is not configured or unreachable.");
+    }
+
+    public static function restoreFailed(string $reason): self
+    {
+        return new self("Backup restore failed: {$reason}");
+    }
+}