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/static/css/dashboard.css

@@ -192,7 +192,7 @@
     font-weight: 400;
     opacity: 0.45;
     line-height: 1.1;
-    color: #4CAF50;
+    color: var(--primary-color);
 }
 
 .dashboard-target-actions {
@@ -258,7 +258,7 @@
     border-radius: 10px;
     font-size: 0.7rem;
     font-weight: 600;
-    background: var(--success-color);
+    background: var(--primary-color);
     color: #fff;
     flex-shrink: 0;
 }