Update error handling and UI design across multiple files

Enhanced error handling in documentation and blog pages, to ensure smoother running and user experience. This also includes additional UI updates related to font selection, layout arrangement, and interactive elements on error pages, marketing pages, and general site navigation components. Moreover, a "contact us" feature has been added to error pages to help users seek assistance more conveniently.

apps/web/app/(marketing)/_components/site-header.tsx

@@ -9,7 +9,7 @@ export function SiteHeader(props: { user?: User | null }) {
   return (
     <div
       className={
-        'sticky top-0 z-10 w-full bg-background/80 backdrop-blur-md dark:bg-background/50 py-2 site-header'
+        'site-header sticky top-0 z-10 w-full bg-background/80 py-2 backdrop-blur-md dark:bg-background/50'
       }
     >
       <div className={'container'}>