feat(classes): optimize teacher dashboard ui and implement grade management

src/app/(dashboard)/teacher/exams/all/page.tsx

@@ -131,13 +131,6 @@ export default async function AllExamsPage({
 }) {
   return (
     <div className="flex h-full flex-col space-y-8 p-8">
-      <div className="flex flex-col justify-between space-y-4 md:flex-row md:items-center md:space-y-0">
-        <div>
-          <h2 className="text-2xl font-bold tracking-tight">All Exams</h2>
-          <p className="text-muted-foreground">View and manage all your exams.</p>
-        </div>
-      </div>
-
       <div className="space-y-4">
         <Suspense fallback={<div className="h-10 w-full animate-pulse rounded-md bg-muted" />}>
           <ExamFilters />