fix(nav): 修复问答梳理等带子路径页面的导航高亮丢失问题

KnowledgeBasePage 加载后自动跳转至 /knowledge/:noteId，原精确路径匹配
导致顶栏和侧边栏选中态丢失。将 hasActiveChild / isItemActive /
menuItemContainsPath 等 8 处判断统一改为前缀匹配
（pathname === path || pathname.startsWith(path + "/")），
覆盖浅色侧边栏、深色侧边栏、顶部导航栏三套组件。

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

frontend-web/src/components/workspace/workspace-sidebar.tsx

@@ -44,7 +44,7 @@ export function WorkspaceSidebar({
           variant="sidebar"
           collapsible="none"
           className={cn(
-            "h-full w-(--sidebar-width)",
+            "h-full w-(--sidebar-width) border-r border-border",
             useWhiteSidebar &&
               "[&_[data-slot=sidebar-inner]]:bg-white [&_[data-slot=sidebar-container]]:bg-white",
             className,