Frontend polish: loading states, CSS variables, focus indicators, scroll lock

- Add tab refresh loading bar animation for all 4 tab loaders
- Add profiles loading guard to prevent concurrent fetches
- Centralize theme colors into CSS variables (--text-secondary, --text-muted,
  --bg-secondary, --success-color, --shadow-color) for both dark/light themes
- Replace hardcoded gray values across 10 CSS files with variables
- Fix duplicate .btn-sm definition in modal.css
- Fix z-index: toast 2001→2500 to safely clear modals at 2000
- Add :focus-visible keyboard navigation indicators for all interactive elements
- Add responsive breakpoints for tab bar and header on narrow screens
- Prevent background page scroll when command palette is open

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

server/src/wled_controller/static/js/features/profiles.js

@@ -2,10 +2,10 @@
  * Profiles — profile cards, editor, condition builder, process picker.
  */
 
-import { apiKey, _profilesCache, set_profilesCache } from '../core/state.js';
+import { apiKey, _profilesCache, set_profilesCache, _profilesLoading, set_profilesLoading } from '../core/state.js';
 import { fetchWithAuth, escapeHtml } from '../core/api.js';
 import { t } from '../core/i18n.js';
-import { showToast, showConfirm } from '../core/ui.js';
+import { showToast, showConfirm, setTabRefreshing } from '../core/ui.js';
 import { Modal } from '../core/modal.js';
 import { CardSection } from '../core/card-sections.js';
 import { updateTabBadge } from './tabs.js';
@@ -41,8 +41,11 @@ document.addEventListener('server:profile_state_changed', () => {
 });
 
 export async function loadProfiles() {
+    if (_profilesLoading) return;
+    set_profilesLoading(true);
     const container = document.getElementById('profiles-content');
-    if (!container) return;
+    if (!container) { set_profilesLoading(false); return; }
+    setTabRefreshing('profiles-content', true);
 
     try {
         const [profilesResp, targetsResp] = await Promise.all([
@@ -67,6 +70,9 @@ export async function loadProfiles() {
         if (error.isAuth) return;
         console.error('Failed to load profiles:', error);
         container.innerHTML = `<p class="error-message">${error.message}</p>`;
+    } finally {
+        set_profilesLoading(false);
+        setTabRefreshing('profiles-content', false);
     }
 }