feat: 侧边栏分组图标与导航样式优化

- 分组支持 icon 字段，可按名称自动匹配或手动选择
- 左侧导航与总览卡片显示彩色 SVG 图标
- 优化侧栏链接圆角与选中态样式

Co-authored-by: Cursor <cursoragent@cursor.com>

static/style.css

@@ -170,37 +170,130 @@ a:hover {
 }
 
 .sidebar-section {
-  margin-bottom: 1rem;
+  margin-bottom: 0.35rem;
+  padding: 0 0.55rem;
 }
 
-.sidebar-section h2 {
-  margin: 0 0 0.35rem;
-  padding: 0 1rem;
-  font-size: 0.72rem;
-  text-transform: uppercase;
-  letter-spacing: 0.08em;
-  color: var(--muted);
+.sidebar-group-title {
+  display: flex;
+  align-items: center;
+  gap: 0.55rem;
+  margin: 0.85rem 0 0.45rem;
+  padding: 0.35rem 0.5rem;
+  font-size: 0.78rem;
   font-weight: 600;
+  letter-spacing: 0.02em;
+  color: var(--text);
+  text-transform: none;
+}
+
+.sidebar-group-name {
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.sidebar-group-icon {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 1.75rem;
+  height: 1.75rem;
+  border-radius: 8px;
+  flex-shrink: 0;
+}
+
+.sidebar-group-icon svg {
+  width: 1rem;
+  height: 1rem;
+}
+
+.sidebar-group-icon--order {
+  background: rgba(59, 130, 246, 0.16);
+  color: #60a5fa;
+}
+
+.sidebar-group-icon--trade {
+  background: rgba(16, 185, 129, 0.16);
+  color: #34d399;
+}
+
+.sidebar-group-icon--review {
+  background: rgba(168, 85, 247, 0.16);
+  color: #c084fc;
+}
+
+.sidebar-group-icon--api {
+  background: rgba(245, 158, 11, 0.16);
+  color: #fbbf24;
+}
+
+.sidebar-group-icon--gate {
+  background: rgba(236, 72, 153, 0.16);
+  color: #f472b6;
+}
+
+.sidebar-group-icon--chart {
+  background: rgba(45, 212, 191, 0.16);
+  color: #2dd4bf;
+}
+
+.sidebar-group-icon--server {
+  background: rgba(99, 102, 241, 0.16);
+  color: #818cf8;
+}
+
+.sidebar-group-icon--folder {
+  background: rgba(148, 163, 184, 0.14);
+  color: #94a3b8;
+}
+
+.sidebar-links {
+  display: flex;
+  flex-direction: column;
+  gap: 0.12rem;
+}
+
+.sidebar-empty {
+  padding: 0.35rem 0.65rem 0.5rem;
+  font-size: 0.82rem;
 }
 
 .nav-link {
-  display: block;
-  padding: 0.45rem 1rem;
+  display: flex;
+  align-items: center;
+  margin: 0;
+  padding: 0.52rem 0.7rem 0.52rem 0.85rem;
   color: var(--text);
   cursor: pointer;
-  border-left: 3px solid transparent;
-  font-size: 0.9rem;
+  border-left: none;
+  border-radius: 8px;
+  font-size: 0.88rem;
   text-decoration: none;
+  transition:
+    background 0.15s ease,
+    color 0.15s ease,
+    box-shadow 0.15s ease;
+}
+
+.nav-link-text {
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
 }
 
 .nav-link:hover {
-  background: rgba(61, 139, 253, 0.08);
+  background: rgba(61, 139, 253, 0.1);
   text-decoration: none;
 }
 
 .nav-link.active {
-  background: rgba(61, 139, 253, 0.15);
-  border-left-color: var(--accent);
+  background: rgba(61, 139, 253, 0.18);
+  box-shadow: inset 3px 0 0 var(--accent);
   text-decoration: none;
 }
 
@@ -232,12 +325,25 @@ a:hover {
 }
 
 .dash-section-title {
+  display: flex;
+  align-items: center;
+  gap: 0.55rem;
   margin: 0 0 0.85rem;
-  font-size: 0.72rem;
+  font-size: 0.95rem;
   font-weight: 600;
-  text-transform: uppercase;
-  letter-spacing: 0.1em;
-  color: var(--muted);
+  letter-spacing: 0.02em;
+  color: var(--text);
+  text-transform: none;
+}
+
+.dash-section-title .sidebar-group-icon {
+  width: 2rem;
+  height: 2rem;
+}
+
+.dash-section-title .sidebar-group-icon svg {
+  width: 1.05rem;
+  height: 1.05rem;
 }
 
 .service-card-grid {