feat: add tenant theme templates

apps/taro/src/pages/tenant-admin/admin.css

@@ -107,6 +107,15 @@
   background: #fff;
 }
 
+.admin-metric.theme-template {
+  cursor: pointer;
+}
+
+.admin-metric.theme-template.selected {
+  border-color: #2563eb;
+  box-shadow: 0 0 0 2px #bfdbfe;
+}
+
 .admin-metric-label {
   display: block;
   color: #64748b;
@@ -230,6 +239,60 @@
   font-size: 22px;
 }
 
+.theme-swatch-row {
+  display: flex;
+  gap: 10px;
+  margin-bottom: 14px;
+}
+
+.theme-swatch {
+  width: 54px;
+  height: 54px;
+  border: 1px solid #e2e8f0;
+  border-radius: 8px;
+}
+
+.theme-preview-panel {
+  margin-top: 14px;
+  overflow: hidden;
+  border: 1px solid #dbe3ef;
+  border-radius: 8px;
+  background: #fff;
+}
+
+.theme-preview-banner {
+  min-height: 134px;
+  padding: 22px;
+}
+
+.theme-preview-title {
+  display: block;
+  color: #fff;
+  font-size: 30px;
+  font-weight: 800;
+  line-height: 1.25;
+}
+
+.theme-preview-subtitle {
+  display: block;
+  margin-top: 10px;
+  color: rgba(255, 255, 255, 0.86);
+  font-size: 22px;
+}
+
+.theme-preview-actions {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  padding: 16px 20px;
+}
+
+.theme-preview-pill {
+  width: 88px;
+  height: 34px;
+  border-radius: 8px;
+}
+
 .break-line {
   word-break: break-all;
   overflow-wrap: anywhere;