docs: clarify no synthetic change-event needed in Salary sync block

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/templates/core/payroll_dashboard.html

@@ -1964,6 +1964,7 @@ document.addEventListener('DOMContentLoaded', function() {
         var _ptFilter = document.getElementById('addAdjPayTypeFilter');
         if (_ptFilter) {
             var _isSalary = (addAdjType.value === 'Salary');
+            // Set .value directly — we do the row hide/show inline below, so a synthetic 'change' dispatch is deliberately not needed.
             _ptFilter.value = _isSalary ? 'fixed' : '';
             addAdjWorkerCheckboxes.forEach(function(cb) {
                 var row = cb.closest('.form-check');