Fix Chrome dialog auto-dismiss with Bootstrap modals

- Add modal-alerts.js library with Bootstrap modal replacements
- Replace all 15 confirm() calls with showConfirm/showDeleteConfirm
- Auto-override window.alert() for all alert() calls
- Fixes Chrome 132+ aggressively blocking native dialogs

weed/admin/view/layout/layout.templ

@@ -357,6 +357,8 @@ templ Layout(c *gin.Context, content templ.Component) {
 
     <!-- Bootstrap JS -->
     <script src="/static/js/bootstrap.bundle.min.js"></script>
+    <!-- Modal Alerts JS (replaces native alert/confirm) -->
+    <script src="/static/js/modal-alerts.js"></script>
     <!-- Custom JS -->
     <script src="/static/js/admin.js"></script>
 </body>