Add support for locking clause syntax (FOR UPDATE and similar)

Author: JanJakes

tests/WP_SQLite_Driver_Tests.php

@@ -6868,6 +6868,7 @@ public function testUpdateWithJoinComplexQuery(): void {
 				WHERE claim_id = 0 AND scheduled_date_gmt <= '2025-09-03 12:23:55' AND status = 'pending'
 				ORDER BY priority ASC, attempts ASC, scheduled_date_gmt ASC, action_id ASC
 				LIMIT 25
+				FOR UPDATE
 			) t2 ON t1.action_id = t2.action_id
 			SET claim_id = 37, last_attempt_gmt = '2025-09-03 12:23:55', last_attempt_local = '2025-09-03 12:23:55'"
 		);

wp-includes/sqlite-ast/class-wp-sqlite-driver.php

@@ -2841,6 +2841,10 @@ private function translate( $node ): ?string {
 			case 'indexHint':
 			case 'indexHintList':
 				return null;
+			case 'lockingClause':
+				// SQLite doesn't support locking clauses (SELECT ... FOR UPDATE).
+				// They are not needed in SQLite due to the database file locking.
+				return null;
 			default:
 				return $this->translate_sequence( $node->get_children() );
 		}