docs: add PHPDoc to syslog_apply_selected_items_action for PHPStan

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

Author: somethingwithproof

functions.php

@@ -126,6 +126,17 @@ function syslog_sendemail($to, $from, $subject, $message, $smsmessage = '') {
 	}
 }
 
+/**
+ * Dispatch a bulk action on selected items from a form submission.
+ *
+ * @param  array|false $selected_items Unserialized selected item IDs, or false
+ * @param  int         $drp_action     The dropdown action identifier
+ * @param  array       $action_map     Map of action IDs to handler function names
+ * @param  string      $export_action  The action ID that triggers CSV export
+ * @param  string      $export_items   Comma-separated item IDs for export
+ *
+ * @return void
+ */
 function syslog_apply_selected_items_action($selected_items, $drp_action, $action_map, $export_action = '', $export_items = '') {
 	if ($selected_items != false) {
 		if (isset($action_map[$drp_action])) {