feat: 控制台旁添加用户头像+下拉菜单(个人资料/退出登录)

css/common.css

@@ -138,6 +138,81 @@ header:hover {
   text-decoration: none;
 }
 
+/* ============================================
+   用户头像 & 下拉菜单
+   ============================================ */
+
+.user-avatar-wrap {
+  position: relative;
+  margin-left: 12px;
+}
+
+.user-avatar {
+  width: 36px;
+  height: 36px;
+  border-radius: 50%;
+  background: #3B82F6;
+  color: #fff;
+  font-size: 15px;
+  font-weight: 600;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+  transition: all 0.2s ease;
+  border: 2px solid rgba(255, 255, 255, 0.2);
+}
+
+.user-avatar:hover {
+  border-color: rgba(255, 255, 255, 0.5);
+  transform: scale(1.05);
+}
+
+.user-dropdown {
+  display: none;
+  position: absolute;
+  top: calc(100% + 8px);
+  right: 0;
+  min-width: 140px;
+  background: #1F2937;
+  border-radius: 12px;
+  padding: 6px 0;
+  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
+  border: 1px solid rgba(255, 255, 255, 0.1);
+  z-index: 1000;
+}
+
+.user-avatar-wrap:hover .user-dropdown {
+  display: block;
+}
+
+/* 下拉箭头 */
+.user-dropdown::before {
+  content: '';
+  position: absolute;
+  top: -6px;
+  right: 12px;
+  width: 12px;
+  height: 12px;
+  background: #1F2937;
+  border-top: 1px solid rgba(255, 255, 255, 0.1);
+  border-left: 1px solid rgba(255, 255, 255, 0.1);
+  transform: rotate(45deg);
+}
+
+.user-dropdown-item {
+  padding: 10px 18px;
+  color: #E5E7EB;
+  font-size: 14px;
+  cursor: pointer;
+  transition: all 0.15s ease;
+}
+
+.user-dropdown-item:hover {
+  background: rgba(255, 255, 255, 0.08);
+  color: #fff;
+}
+
 /* ============================================
    登录注册区域 - 撑满高度设计
    ============================================ */