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/assignments/page.tsx

@@ -1,7 +1,23 @@
+import Link from "next/link"
 import { EmptyState } from "@/shared/components/ui/empty-state"
-import { PenTool } from "lucide-react"
+import { Badge } from "@/shared/components/ui/badge"
+import { Button } from "@/shared/components/ui/button"
+import {
+  Table,
+  TableBody,
+  TableCell,
+  TableHead,
+  TableHeader,
+  TableRow,
+} from "@/shared/components/ui/table"
+import { formatDate } from "@/shared/lib/utils"
+import { getHomeworkAssignments } from "@/modules/homework/data-access"
+import { PenTool, PlusCircle } from "lucide-react"
+
+export default async function AssignmentsPage() {
+  const assignments = await getHomeworkAssignments()
+  const hasAssignments = assignments.length > 0
 
-export default function AssignmentsPage() {
   return (
     <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
       <div className="flex items-center justify-between space-y-2">
@@ -11,16 +27,58 @@ export default function AssignmentsPage() {
             Manage homework assignments.
           </p>
         </div>
+        <Button asChild>
+          <Link href="/teacher/homework/assignments/create">
+            <PlusCircle className="mr-2 h-4 w-4" />
+            Create Assignment
+          </Link>
+        </Button>
       </div>
-      <EmptyState
-        title="No assignments"
-        description="You haven't created any assignments yet."
-        icon={PenTool}
-        action={{
-          label: "Create Assignment",
-          href: "#"
-        }}
-      />
+
+      {!hasAssignments ? (
+        <EmptyState
+          title="No assignments"
+          description="You haven't created any assignments yet."
+          icon={PenTool}
+          action={{
+            label: "Create Assignment",
+            href: "/teacher/homework/assignments/create",
+          }}
+        />
+      ) : (
+        <div className="rounded-md border bg-card">
+          <Table>
+            <TableHeader>
+              <TableRow>
+                <TableHead>Title</TableHead>
+                <TableHead>Status</TableHead>
+                <TableHead>Due</TableHead>
+                <TableHead>Source Exam</TableHead>
+                <TableHead>Created</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {assignments.map((a) => (
+                <TableRow key={a.id}>
+                  <TableCell className="font-medium">
+                    <Link href={`/teacher/homework/assignments/${a.id}`} className="hover:underline">
+                      {a.title}
+                    </Link>
+                  </TableCell>
+                  <TableCell>
+                    <Badge variant="outline" className="capitalize">
+                      {a.status}
+                    </Badge>
+                  </TableCell>
+                  <TableCell>{a.dueAt ? formatDate(a.dueAt) : "-"}</TableCell>
+                  <TableCell className="text-muted-foreground">{a.sourceExamTitle}</TableCell>
+                  <TableCell className="text-muted-foreground">{formatDate(a.createdAt)}</TableCell>
+                </TableRow>
+              ))}
+            </TableBody>
+          </Table>
+        </div>
+      )}
     </div>
   )
 }