Refactor admin dashboard and standardize UI shells

src/TaxBaik.Web/wwwroot/css/admin.css

@@ -497,6 +497,9 @@ textarea:focus-visible {
   border-right: 1px solid var(--border-color);
   display: flex;
   flex-direction: column;
+  position: sticky;
+  top: 0;
+  height: 100vh;
 }
 
 .admin-drawer-brand {
@@ -539,6 +542,23 @@ textarea:focus-visible {
   font-size: 0.78rem;
 }
 
+.admin-nav .mud-nav-link .mud-stack {
+  width: 100%;
+  gap: 8px;
+}
+
+.admin-nav-badge {
+  margin-left: auto;
+  height: 18px;
+  font-size: 0.65rem;
+}
+
+.admin-body {
+  display: flex;
+  min-height: 0;
+  flex: 1;
+}
+
 .admin-nav .mud-nav-group-header {
   min-height: 32px;
   font-size: 0.78rem;
@@ -618,6 +638,130 @@ textarea:focus-visible {
   width: 100%;
 }
 
+.admin-dashboard-grid {
+  margin-top: 0;
+}
+
+.admin-stats-grid {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 12px;
+}
+
+.admin-stat {
+  padding: 14px;
+  border: 1px solid var(--border-color-light);
+  border-radius: var(--radius-lg);
+  background: linear-gradient(180deg, #fff 0%, #f8fbff 100%);
+}
+
+.admin-stat-label {
+  display: block;
+  margin-bottom: 4px;
+  color: var(--text-secondary);
+  font-size: 0.75rem;
+}
+
+.admin-stat-value {
+  font-size: 1.25rem;
+  font-weight: 700;
+  color: var(--text-primary);
+}
+
+.admin-chart {
+  margin-top: 14px;
+  padding: 14px;
+  border: 1px solid var(--border-color-light);
+  border-radius: var(--radius-lg);
+  background: #fff;
+}
+
+.admin-chart-header {
+  display: flex;
+  justify-content: space-between;
+  gap: 12px;
+  margin-bottom: 12px;
+  font-size: 0.8rem;
+  color: var(--text-secondary);
+}
+
+.admin-chart-bars {
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+
+.admin-chart-row {
+  display: grid;
+  grid-template-columns: 56px 1fr 28px;
+  gap: 10px;
+  align-items: center;
+  font-size: 0.75rem;
+}
+
+.admin-chart-track {
+  height: 10px;
+  background: var(--bg-tertiary);
+  border-radius: var(--radius-full);
+  overflow: hidden;
+}
+
+.admin-chart-fill {
+  height: 100%;
+  border-radius: inherit;
+}
+
+.admin-quick-grid {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 12px;
+}
+
+.admin-quick-card {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  padding: 14px;
+  border: 1px solid var(--border-color-light);
+  border-radius: var(--radius-lg);
+  cursor: pointer;
+  transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
+  background: linear-gradient(180deg, #fff 0%, #f8fbff 100%);
+}
+
+.admin-quick-card:hover {
+  transform: translateY(-2px);
+  box-shadow: var(--shadow-md);
+  border-color: var(--border-color-strong);
+}
+
+.admin-quick-card .mud-icon-root {
+  color: var(--primary-color);
+}
+
+.admin-note-list {
+  display: grid;
+  gap: 10px;
+  color: var(--text-secondary);
+  font-size: 0.8rem;
+}
+
+.admin-note-list div {
+  padding-left: 14px;
+  position: relative;
+}
+
+.admin-note-list div::before {
+  content: '';
+  position: absolute;
+  left: 0;
+  top: 0.55em;
+  width: 6px;
+  height: 6px;
+  border-radius: 9999px;
+  background: var(--primary-color);
+}
+
 /* ============================================================================
    Dashboard Page Styles
    ============================================================================ */