Make createDatabase idempotent: drop leftovers from failed attempts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Services/InstanceProvisionerService.php

@@ -71,6 +71,10 @@ private function createDatabase(string $dbName, string $dbUser, string $dbPasswo
         $adminConn = config('manager.shared_pg_admin_connection');
         $escapedPassword = str_replace("'", "''", $dbPassword);
 
+        // Idempotent: drop leftovers from failed previous attempts
+        DB::connection($adminConn)->statement("DROP DATABASE IF EXISTS \"{$dbName}\"");
+        DB::connection($adminConn)->statement("DROP USER IF EXISTS \"{$dbUser}\"");
+
         DB::connection($adminConn)->statement("CREATE USER \"{$dbUser}\" WITH PASSWORD '{$escapedPassword}'");
         DB::connection($adminConn)->statement("CREATE DATABASE \"{$dbName}\" OWNER \"{$dbUser}\"");
         DB::connection($adminConn)->statement("GRANT ALL PRIVILEGES ON DATABASE \"{$dbName}\" TO \"{$dbUser}\"");