feat: improve page component (#5013)

* feat: `page` component support fixed header

* docs: `page`  component documentation

* docs: Improve `props` types of `page`

* docs: improve `fixedHeader` description of `page`

* fix: `page` header border color with fixedHeader

* feat: add `headerClass` for `Page`

packages/@core/ui-kit/layout-ui/src/vben-layout.vue

@@ -503,7 +503,7 @@ function handleHeaderToggle() {
 
     <div
       ref="contentRef"
-      class="flex flex-1 flex-col overflow-hidden transition-all duration-300 ease-in"
+      class="flex flex-1 flex-col transition-all duration-300 ease-in"
     >
       <div
         :class="[