Comprehensive WebUI review: 41 UX/feature/CSS improvements

Safety & Correctness:
- Add confirmation dialogs to Stop All, turnOffDevice
- i18n confirm dialog (title, yes, no buttons)
- Fix duplicate tutorial-overlay ID
- Define missing CSS variables (--radius, --text-primary, --hover-bg, --input-bg)
- Fix toast z-index conflict with confirm dialog (2500 → 3000)

UX Consistency:
- Add backdrop-close to test modals
- Add device clone feature (only entity without it)
- Add sync clocks to command palette
- Replace 20+ hardcoded accent colors with CSS vars/color-mix()
- Remove dead .badge duplicate from components.css
- Make calibration elements keyboard-accessible (div → button)
- Add aria-labels to color picker swatches
- Fix pattern canvas mobile horizontal scroll
- Fix graph editor mobile bottom clipping

Polish:
- Add empty-state messages to all CardSection instances
- Convert 21 px font-sizes to rem
- Add scroll-behavior: smooth with reduced-motion override
- Add @media print styles
- Add :focus-visible to 4 missing interactive elements
- Fix settings modal close label (Cancel → Close)
- Fix api-key submit button i18n

New Features:
- Command palette actions: start/stop targets, activate scenes, enable/disable
- Bulk start/stop API endpoints (POST /output-targets/bulk/start|stop)
- OS notification history viewer modal
- Scene "used by" automation reference count on cards
- Clock elapsed time display on Streams tab cards
- Device "last seen" relative timestamp on cards
- Audio device refresh button in edit modal
- Composite layer drag-to-reorder
- MQTT settings panel (broker config with JSON persistence)
- WebSocket log viewer with level filtering and ring buffer
- Runtime log-level adjustment (GET/PUT endpoints + settings UI)
- Animated value source waveform canvas preview
- Gradient custom preset save/delete (localStorage)
- API key read-only display in settings
- Backup metadata (file size, auto/manual badges)
- Server restart button with confirm + overlay
- Partial config export/import per entity type
- Progressive disclosure in target editor (Advanced section)

CSS Architecture:
- Define radius scale tokens (--radius-sm/md/lg/pill)
- Scope .cs-filter selectors to remove 7 !important overrides
- Consolidate duplicate toggle switch (filter-list → settings-toggle)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/wled_controller/static/js/features/scene-presets.js

@@ -11,7 +11,7 @@ import { CardSection } from '../core/card-sections.js';
 import {
     ICON_SCENE, ICON_CAPTURE, ICON_START, ICON_EDIT, ICON_REFRESH, ICON_TARGET, ICON_CLONE,
 } from '../core/icons.js';
-import { scenePresetsCache, outputTargetsCache } from '../core/state.js';
+import { scenePresetsCache, outputTargetsCache, automationsCacheObj } from '../core/state.js';
 import { TagInput, renderTagChips } from '../core/tag-input.js';
 import { cardColorStyle, cardColorButton } from '../core/card-colors.js';
 import { EntityPalette } from '../core/entity-palette.js';
@@ -43,13 +43,18 @@ export const csScenes = new CardSection('scenes', {
     gridClass: 'devices-grid',
     addCardOnclick: "openScenePresetCapture()",
     keyAttr: 'data-scene-id',
+    emptyKey: 'section.empty.scenes',
 });
 
 export function createSceneCard(preset) {
     const targetCount = (preset.targets || []).length;
 
+    const automations = automationsCacheObj.data || [];
+    const usedByCount = automations.filter(a => a.scene_preset_id === preset.id).length;
+
     const meta = [
         targetCount > 0 ? `${ICON_TARGET} ${targetCount} ${t('scenes.targets_count')}` : null,
+        usedByCount > 0 ? `🔗 ${t('scene_preset.used_by').replace('%d', usedByCount)}` : null,
     ].filter(Boolean);
 
     const updated = preset.updated_at ? new Date(preset.updated_at).toLocaleString() : '';