Show rows for all reads and confirm nextval()

SHOW, EXPLAIN, VALUES and TABLE count as reads now but their rows were
dropped and reported as a write; every read except SET now returns its
rows. nextval() advances a sequence, so it needs confirmation like
setval().

lib/Controller/DbController.php

@@ -174,7 +174,7 @@ class DbController extends Controller
                 $stmt = $this->db->prepare($query);
                 $stmt->execute();
 
-                if ($statementType === 'SELECT' || ($statementType === 'WITH' && SqlGuard::isReadOnly($query))) {
+                if ($statementType === 'SELECT' || ($statementType !== 'SET' && SqlGuard::isReadOnly($query))) {
                     // Read row by row and stop at MAX_ROWS, instead of
                     // fetchAll() + array_slice — otherwise a SELECT without
                     // LIMIT on a huge table would still pull everything into

lib/Service/SqlGuard.php

@@ -46,7 +46,7 @@ class SqlGuard
     private const WRITES_INSIDE_READ = [
         '/\b(INSERT|UPDATE|DELETE|MERGE|INTO|ANALYZE)\b/i',
         '/^SET\s+(SESSION\s+|LOCAL\s+)?(ROLE|SESSION\s+AUTHORIZATION)\b/i',
-        '/\b(pg_terminate_backend|pg_cancel_backend|pg_reload_conf|set_config|setval|lo_create|lo_put|lo_unlink|pg_switch_wal|pg_create_restore_point|pg_advisory_lock)\s*\(/i',
+        '/\b(pg_terminate_backend|pg_cancel_backend|pg_reload_conf|set_config|setval|nextval|lo_create|lo_put|lo_unlink|pg_switch_wal|pg_create_restore_point|pg_advisory_lock)\s*\(/i',
     ];
 
     /**