Replace all emoji icons with Lucide SVGs, add accent color picker

- Replace all emoji characters across WebUI with inline Lucide SVG icons
  for cross-platform consistency (icon paths in icon-paths.js)
- Add accent color picker popover with 9 preset colors + custom picker,
  persisted to localStorage, updates all CSS custom properties
- Remove subtab separator line for cleaner look
- Color badge icons with accent color for visual pop
- Remove processing badge from target cards
- Fix hardcoded #4CAF50 in FPS labels and active badges to use CSS vars
- Replace CSS content emoji (▶) with pure CSS triangle

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

server/src/wled_controller/templates/modals/device-settings.html

@@ -2,7 +2,7 @@
 <div id="device-settings-modal" class="modal" role="dialog" aria-modal="true" aria-labelledby="device-settings-modal-title">
     <div class="modal-content">
         <div class="modal-header">
-            <h2 id="device-settings-modal-title" data-i18n="settings.general.title">⚙️ General Settings</h2>
+            <h2 id="device-settings-modal-title"><svg class="icon" viewBox="0 0 24 24"><path d="M9.671 4.136a2.34 2.34 0 0 1 4.659 0 2.34 2.34 0 0 0 3.319 1.915 2.34 2.34 0 0 1 2.33 4.033 2.34 2.34 0 0 0 0 3.831 2.34 2.34 0 0 1-2.33 4.033 2.34 2.34 0 0 0-3.319 1.915 2.34 2.34 0 0 1-4.659 0 2.34 2.34 0 0 0-3.32-1.915 2.34 2.34 0 0 1-2.33-4.033 2.34 2.34 0 0 0 0-3.831A2.34 2.34 0 0 1 6.35 6.051a2.34 2.34 0 0 0 3.319-1.915"/><circle cx="12" cy="12" r="3"/></svg> <span data-i18n="settings.general.title">General Settings</span></h2>
             <button class="modal-close-btn" onclick="closeDeviceSettingsModal()" title="Close" data-i18n-aria-label="aria.close">&#x2715;</button>
         </div>
         <div class="modal-body">