Merge exams grading into homework

Redirect /teacher/exams/grading* to /teacher/homework/submissions; remove exam grading UI/actions/data-access; add homework student workflow and update design docs.

src/app/(dashboard)/teacher/exams/grading/[submissionId]/page.tsx

@@ -1,40 +1,6 @@
-import { notFound } from "next/navigation"
-import { GradingView } from "@/modules/exams/components/grading-view"
-import { getSubmissionDetails } from "@/modules/exams/data-access"
-import { formatDate } from "@/shared/lib/utils"
+import { redirect } from "next/navigation"
 
 export default async function SubmissionGradingPage({ params }: { params: Promise<{ submissionId: string }> }) {
-  const { submissionId } = await params
-  const submission = await getSubmissionDetails(submissionId)
-
-  if (!submission) {
-    return notFound()
-  }
-
-  return (
-    <div className="flex h-full flex-col space-y-4 p-6">
-      <div className="flex items-center justify-between">
-        <div>
-          <h2 className="text-2xl font-bold tracking-tight">{submission.examTitle}</h2>
-          <div className="flex items-center gap-4 text-sm text-muted-foreground mt-1">
-            <span>Student: <span className="font-medium text-foreground">{submission.studentName}</span></span>
-            <span>•</span>
-            <span>Submitted: {submission.submittedAt ? formatDate(submission.submittedAt) : "-"}</span>
-            <span>•</span>
-            <span className="capitalize">Status: {submission.status}</span>
-          </div>
-        </div>
-      </div>
-
-      <GradingView 
-        submissionId={submission.id}
-        studentName={submission.studentName}
-        examTitle={submission.examTitle}
-        submittedAt={submission.submittedAt}
-        status={submission.status || "started"}
-        totalScore={submission.totalScore}
-        answers={submission.answers}
-      />
-    </div>
-  )
+  await params
+  redirect("/teacher/homework/submissions")
 }