feat: add lucide-react icons and redesign admin UI with enhanced visual hierarchy

Add lucide-react dependency and create app-icons module with icon mappings for all admin sections. Replace logo images with inline SVG brand glyph component.

Update Layout component with icon-enhanced navigation links including chevron indicators and hover states. Add topbar icon wrapper with gradient background styling.

Redesign Page component header with icon, eyebrow text, and improved title block layout. Add page

admin-web/package.json

@@ -10,6 +10,7 @@
   },
   "dependencies": {
     "@tanstack/react-query": "^5.66.8",
+    "lucide-react": "^0.511.0",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-router-dom": "^6.30.0"