refactor: extract shared form utils, add aria-live regions and reduced-motion support

DRY duplicated helpers (escapeAttr, belongsToForm, isSubmitControl,
isEditableTarget) into web/js/core/app-form-utils.js and update 7
consumers. Add aria-live="polite" to flash messages, async messages,
and search results for screen reader announcements. Add
prefers-reduced-motion support to CSS tooltips.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/js/components/app-confirm-actions.js

@@ -2,6 +2,7 @@
  * Declarative confirm-before-action — intercepts clicks and submits on [data-confirm-message] elements.
  */
 import { confirmDialog, requestSubmitWithFallback } from '../core/app-confirm-dialog.js';
+import { isSubmitControl, belongsToForm } from '../core/app-form-utils.js';
 
 const CONFIRM_ATTR = 'data-confirm-message';
 const confirmedSubmitterByForm = new WeakMap();
@@ -9,37 +10,7 @@ const confirmedClickElements = new WeakSet();
 
 const trimAttr = (element, attr) => String(element?.getAttribute(attr) || '').trim();
 
-const isSubmitControl = (element) => {
-  if (!(element instanceof HTMLElement)) {
-    return false;
-  }
-  if (element instanceof HTMLButtonElement) {
-    const type = String(element.getAttribute('type') || 'submit').trim().toLowerCase();
-    return type === '' || type === 'submit';
-  }
-  if (element instanceof HTMLInputElement) {
-    const type = String(element.type || '').trim().toLowerCase();
-    return type === 'submit' || type === 'image';
-  }
-  return false;
-};
-
 const submitterByForm = new Map();
-const belongsToForm = (control, form) => {
-  if (!(control instanceof HTMLElement) || !(form instanceof HTMLFormElement)) {
-    return false;
-  }
-  const owner = control.form;
-  if (owner instanceof HTMLFormElement) {
-    return owner === form;
-  }
-  const controlFormAttr = trimAttr(control, 'form');
-  const formId = trimAttr(form, 'id');
-  if (controlFormAttr !== '' && formId !== '') {
-    return controlFormAttr === formId;
-  }
-  return form.contains(control);
-};
 
 const readConfirmOption = (primary, fallback, suffix) => {
   const attr = `data-confirm-${suffix}`;

web/js/components/app-global-search.js

@@ -2,6 +2,7 @@
  * Global search sidebar — debounced fetch with live result counts and Ctrl+K shortcut.
  */
 import { requireEl, optionalEl, warnOnce } from '../core/app-dom.js';
+import { isEditableTarget } from '../core/app-form-utils.js';
 
 const input = requireEl('#side-search', { module: 'global-search' });
 const resultsEl = requireEl('[data-global-search-results]', { module: 'global-search' });
@@ -191,13 +192,6 @@ if (input && resultsEl) {
     submitSearch();
   });
 
-  const isEditableTarget = (target) => {
-    if (!target) {return false;}
-    if (target.isContentEditable) {return true;}
-    const tag = target.tagName;
-    return tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT';
-  };
-
   const focusSearch = () => {
     if (!input) {return;}
     window.requestAnimationFrame(() => {

web/js/components/app-nav-history.js

@@ -1,6 +1,8 @@
 /**
  * Browser history integration — handles back/forward navigation state.
  */
+import { isEditableTarget } from '../core/app-form-utils.js';
+
 const updateHistoryButtons = () => {
   const back = document.querySelector('#global-back');
   const forward = document.querySelector('#global-forward');
@@ -29,13 +31,6 @@ const initHistoryButtons = () => {
   const back = document.querySelector('#global-back');
   const forward = document.querySelector('#global-forward');
 
-  const isEditableTarget = (target) => {
-    if (!target) {return false;}
-    if (target.isContentEditable) {return true;}
-    const tag = target.tagName;
-    return tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT';
-  };
-
   document.addEventListener('keydown', (event) => {
     if (!event.altKey || event.metaKey || event.ctrlKey) {return;}
     if (isEditableTarget(event.target)) {return;}

web/js/components/app-toggle-aside-panels.js

@@ -2,6 +2,7 @@
  * Aside panel switcher — opens/closes named sidebar panels.
  */
 import { requireEl, warnOnce } from '../core/app-dom.js';
+import { isEditableTarget } from '../core/app-form-utils.js';
 import { initPersistedDetailsGroup } from '../core/app-details-open-state.js';
 
 export function initAsidePanels(options = {}) {
@@ -40,12 +41,6 @@ export function initAsidePanels(options = {}) {
   const getTabKey = (tab) => tab?.dataset?.asideTarget || '';
   const getPanelTools = (panel) => panel?.querySelector('[data-aside-panel-tools]') || null;
   const getTabHref = (tab) => tab?.dataset?.asideHref || '';
-  const isEditableTarget = (target) => {
-    if (!target) {return false;}
-    if (target.isContentEditable) {return true;}
-    const tag = target.tagName;
-    return tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT';
-  };
 
   const panelDetailsRegistry = new WeakMap();
   const findActiveDetailsKeys = (panel) => Array.from(panel.querySelectorAll('details[data-details-key]'))

web/js/components/app-toggle-sidebar.js

@@ -2,6 +2,7 @@
  * Sidebar collapse/show toggle with localStorage persistence and Ctrl+B shortcut.
  */
 import { requireEl, warnOnce } from '../core/app-dom.js';
+import { isEditableTarget } from '../core/app-form-utils.js';
 
 export function initSidebarToggle(options = {}) {
   const {
@@ -150,13 +151,6 @@ export function initSidebarToggle(options = {}) {
   return controller;
 }
 
-const isEditableTarget = (target) => {
-  if (!target) {return false;}
-  if (target.isContentEditable) {return true;}
-  const tag = target.tagName;
-  return tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT';
-};
-
 document.addEventListener('keydown', (event) => {
   if (!(event.metaKey || event.ctrlKey)) {return;}
   if (event.altKey) {return;}