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/homework/submissions/[submissionId]/page.tsx

@@ -0,0 +1,41 @@
+import { notFound } from "next/navigation"
+import { getHomeworkSubmissionDetails } from "@/modules/homework/data-access"
+import { HomeworkGradingView } from "@/modules/homework/components/homework-grading-view"
+import { formatDate } from "@/shared/lib/utils"
+
+export default async function HomeworkSubmissionGradingPage({ params }: { params: Promise<{ submissionId: string }> }) {
+  const { submissionId } = await params
+  const submission = await getHomeworkSubmissionDetails(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.assignmentTitle}</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>
+
+      <HomeworkGradingView
+        submissionId={submission.id}
+        studentName={submission.studentName}
+        assignmentTitle={submission.assignmentTitle}
+        submittedAt={submission.submittedAt}
+        status={submission.status}
+        totalScore={submission.totalScore}
+        answers={submission.answers}
+      />
+    </div>
+  )
+}
+