feat: add 9 new dashboard features with export and comparison

- Add Hidden Champions tab with filterable product table
- Add Opportunity Map tab with scatter chart (supply/demand quadrants)
- Add Sales Funnel section to Overview with conversion rates
- Add Price Distribution histogram with mean/median lines
- Add Competition Score gauge (0-100) with 4 sub-metrics
- Add Excel export (3-sheet xlsx) and Print buttons to dashboard
- Add Report Comparison page with KPI diff table and brand bar chart
- Add enrichment UI to ReportList with progress tracking
- Add sidebar navigation with Karşılaştır route
- Refactor UI: Layout, Sidebar, TopBar, KpiCard, SkeletonLoader components
- Improve drill-down UX with visible pill buttons and tooltips

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

admin-panel/src/index.css

@@ -2,16 +2,73 @@
 
 body {
   margin: 0;
-  font-family: system-ui, -apple-system, sans-serif;
+  font-family: 'Inter', system-ui, -apple-system, sans-serif;
+  background-color: #f8fafc; /* slate-50 */
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
 }
 
-/* Hide scrollbar for Chrome, Safari and Opera */
+/* Skeleton loading animation */
+@keyframes skeleton-pulse {
+  0%, 100% { opacity: 1; }
+  50% { opacity: 0.4; }
+}
+
+.skeleton {
+  animation: skeleton-pulse 1.5s cubic-bezier(0.4, 0, 0.6, 1) infinite;
+  background: linear-gradient(90deg, #e2e8f0 25%, #f1f5f9 50%, #e2e8f0 75%);
+  background-size: 200% 100%;
+  animation: skeleton-shimmer 1.5s ease-in-out infinite;
+  border-radius: 0.5rem;
+}
+
+@keyframes skeleton-shimmer {
+  0% { background-position: 200% 0; }
+  100% { background-position: -200% 0; }
+}
+
+/* Custom scrollbar */
+::-webkit-scrollbar {
+  width: 6px;
+  height: 6px;
+}
+
+::-webkit-scrollbar-track {
+  background: transparent;
+}
+
+::-webkit-scrollbar-thumb {
+  background: #cbd5e1; /* slate-300 */
+  border-radius: 3px;
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: #94a3b8; /* slate-400 */
+}
+
+/* Hide scrollbar utility */
 .scrollbar-hide::-webkit-scrollbar {
   display: none;
 }
 
-/* Hide scrollbar for IE, Edge and Firefox */
 .scrollbar-hide {
-  -ms-overflow-style: none;  /* IE and Edge */
-  scrollbar-width: none;  /* Firefox */
+  -ms-overflow-style: none;
+  scrollbar-width: none;
+}
+
+/* Page transition */
+.page-enter {
+  opacity: 0;
+  transform: translateY(8px);
+}
+
+.page-enter-active {
+  opacity: 1;
+  transform: translateY(0);
+  transition: opacity 200ms ease-out, transform 200ms ease-out;
+}
+
+/* Smooth transitions for interactive elements */
+button, a, input, select, textarea {
+  transition: all 150ms ease;
 }