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/css-editor.html

@@ -2,7 +2,7 @@
 <div id="css-editor-modal" class="modal" role="dialog" aria-modal="true" aria-labelledby="css-editor-title">
     <div class="modal-content">
         <div class="modal-header">
-            <h2 id="css-editor-title" data-i18n="color_strip.add">🎞️ Add Color Strip Source</h2>
+            <h2 id="css-editor-title"><svg class="icon" viewBox="0 0 24 24"><rect width="18" height="18" x="3" y="3" rx="2"/><path d="M7 3v18"/><path d="M3 7.5h4"/><path d="M3 12h18"/><path d="M3 16.5h4"/><path d="M17 3v18"/><path d="M17 7.5h4"/><path d="M17 16.5h4"/></svg> <span data-i18n="color_strip.add">Add Color Strip Source</span></h2>
             <button class="modal-close-btn" onclick="closeCSSEditorModal()" title="Close" data-i18n-aria-label="aria.close">&#x2715;</button>
         </div>
         <div class="modal-body">