Frontend: structured error handling, state fixes, accessibility, i18n

- Enhance fetchWithAuth with auto-401, retry w/ exponential backoff, timeout
- Remove ~40 manual 401 checks across 10 feature files
- Fix state: brightness cache setter, manual edit flag resets, static import
- Add ARIA: role=dialog/tablist, aria-modal, aria-labelledby, aria-selected
- Add focus trapping in Modal base class, aria-expanded on hint toggles
- Fix WCAG AA color contrast with --primary-text-color variable
- Add i18n pluralization (CLDR rules for en/ru), getCurrentLocale export
- Replace hardcoded strings in dashboard.js and profiles.js
- Add data-i18n-aria-label support, 20 new keys in en.json and ru.json

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

server/src/wled_controller/static/js/features/kc-targets.js

@@ -9,7 +9,7 @@ import {
     kcWebSockets,
     PATTERN_RECT_BORDERS,
 } from '../core/state.js';
-import { API_BASE, getHeaders, fetchWithAuth, escapeHtml, handle401Error } from '../core/api.js';
+import { API_BASE, getHeaders, fetchWithAuth, escapeHtml } from '../core/api.js';
 import { t } from '../core/i18n.js';
 import { lockBody, showToast, showConfirm } from '../core/ui.js';
 import { Modal } from '../core/modal.js';
@@ -436,10 +436,12 @@ export function isKCEditorDirty() {
 
 export async function closeKCEditorModal() {
     await kcEditorModal.close();
+    set_kcNameManuallyEdited(false);
 }
 
 export function forceCloseKCEditorModal() {
     kcEditorModal.forceClose();
+    set_kcNameManuallyEdited(false);
 }
 
 export async function saveKCEditor() {
@@ -475,22 +477,18 @@ export async function saveKCEditor() {
     try {
         let response;
         if (targetId) {
-            response = await fetch(`${API_BASE}/picture-targets/${targetId}`, {
+            response = await fetchWithAuth(`/picture-targets/${targetId}`, {
                 method: 'PUT',
-                headers: getHeaders(),
                 body: JSON.stringify(payload),
             });
         } else {
             payload.target_type = 'key_colors';
-            response = await fetch(`${API_BASE}/picture-targets`, {
+            response = await fetchWithAuth('/picture-targets', {
                 method: 'POST',
-                headers: getHeaders(),
                 body: JSON.stringify(payload),
             });
         }
 
-        if (response.status === 401) { handle401Error(); return; }
-
         if (!response.ok) {
             const err = await response.json();
             throw new Error(err.detail || 'Failed to save');
@@ -501,6 +499,7 @@ export async function saveKCEditor() {
         // Use window.* to avoid circular import with targets.js
         if (typeof window.loadTargetsTab === 'function') window.loadTargetsTab();
     } catch (error) {
+        if (error.isAuth) return;
         console.error('Error saving KC target:', error);
         kcEditorModal.showError(error.message);
     }
@@ -512,11 +511,9 @@ export async function deleteKCTarget(targetId) {
 
     try {
         disconnectKCWebSocket(targetId);
-        const response = await fetch(`${API_BASE}/picture-targets/${targetId}`, {
+        const response = await fetchWithAuth(`/picture-targets/${targetId}`, {
             method: 'DELETE',
-            headers: getHeaders()
         });
-        if (response.status === 401) { handle401Error(); return; }
         if (response.ok) {
             showToast(t('kc.deleted'), 'success');
             // Use window.* to avoid circular import with targets.js
@@ -526,6 +523,7 @@ export async function deleteKCTarget(targetId) {
             showToast(`Failed to delete: ${error.detail}`, 'error');
         }
     } catch (error) {
+        if (error.isAuth) return;
         showToast('Failed to delete key colors target', 'error');
     }
 }