Add CPU/GPU names on perf charts, reusable color picker, and header toolbar redesign

- Show CPU and GPU model names as overlays on performance chart cards
- Add cpu_name field to performance API with cross-platform detection
- Extract reusable color-picker popover module (9 presets + custom picker)
- Per-chart color customization for CPU/RAM/GPU performance charts
- Redesign header: compact toolbar container with icon-only buttons
- Compact language dropdown (EN/RU/ZH), icon-only login/logout
- Use accent color for FPS charts, range slider accent, dashboard icons

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

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

@@ -29,7 +29,7 @@ const gettingStartedSteps = [
     { selector: '#tab-btn-profiles', textKey: 'tour.profiles', position: 'bottom' },
     { selector: '[onclick*="openSettingsModal"]', textKey: 'tour.settings', position: 'bottom' },
     { selector: '[onclick*="openCommandPalette"]', textKey: 'tour.search', position: 'bottom' },
-    { selector: '.theme-toggle', textKey: 'tour.theme', position: 'bottom' },
+    { selector: '[onclick*="toggleTheme"]', textKey: 'tour.theme', position: 'bottom' },
     { selector: '#locale-select', textKey: 'tour.language', position: 'bottom' }
 ];