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/api-key.html

@@ -2,7 +2,7 @@
 <div id="api-key-modal" class="modal" role="dialog" aria-modal="true" aria-labelledby="api-key-modal-title">
     <div class="modal-content">
         <div class="modal-header">
-            <h2 id="api-key-modal-title" data-i18n="auth.title">🔑 Login to LED Grab</h2>
+            <h2 id="api-key-modal-title"><svg class="icon" viewBox="0 0 24 24"><path d="M2.586 17.414A2 2 0 0 0 2 18.828V21a1 1 0 0 0 1 1h3a1 1 0 0 0 1-1v-1a1 1 0 0 1 1-1h1a1 1 0 0 0 1-1v-1a1 1 0 0 1 1-1h.172a2 2 0 0 0 1.414-.586l.814-.814a6.5 6.5 0 1 0-4-4z"/><circle cx="16.5" cy="7.5" r=".5" fill="currentColor"/></svg> <span data-i18n="auth.title">Login to LED Grab</span></h2>
             <button class="modal-close-btn" id="modal-close-x-btn" onclick="closeApiKeyModal()" title="Close" data-i18n-aria-label="aria.close">&#x2715;</button>
         </div>
         <form id="api-key-form" onsubmit="submitApiKey(event)">
@@ -25,7 +25,7 @@
                             autocomplete="off"
                         >
                         <button type="button" class="password-toggle" onclick="togglePasswordVisibility()">
-                            👁️
+                            <svg class="icon" viewBox="0 0 24 24"><path d="M2.062 12.348a1 1 0 0 1 0-.696 10.75 10.75 0 0 1 19.876 0 1 1 0 0 1 0 .696 10.75 10.75 0 0 1-19.876 0"/><circle cx="12" cy="12" r="3"/></svg>
                         </button>
                     </div>
                 </div>