feat(app): add error/loading boundaries and update dashboard routes

- Add error.tsx and loading.tsx boundaries for admin, parent, student, teacher routes

- Add dashboard-error-fallback and dashboard-loading-skeleton components

- Add student/learning page, parent/leave routes, teacher textbook components

- Update existing app routes across auth, dashboard, and API endpoints

- Update proxy middleware and next-auth type declarations

src/app/(dashboard)/student/learning/page.tsx

@@ -0,0 +1,93 @@
+import Link from "next/link"
+import { BookOpen, PenTool, Library, ArrowRight } from "lucide-react"
+
+import { getStudentClasses } from "@/modules/classes/data-access"
+import { getStudentHomeworkAssignments } from "@/modules/homework/data-access"
+import { getCurrentStudentUser } from "@/modules/users/data-access"
+import { getTextbooks } from "@/modules/textbooks/data-access"
+import { Card, CardContent, CardHeader, CardTitle } from "@/shared/components/ui/card"
+import { EmptyState } from "@/shared/components/ui/empty-state"
+import { UserX } from "lucide-react"
+
+export const dynamic = "force-dynamic"
+
+export default async function StudentLearningPage() {
+  const student = await getCurrentStudentUser()
+  if (!student) {
+    return (
+      <div className="space-y-8">
+        <EmptyState title="No user found" description="Create a student user to see learning." icon={UserX} />
+      </div>
+    )
+  }
+
+  const [classes, assignments, textbooks] = await Promise.all([
+    getStudentClasses(student.id),
+    getStudentHomeworkAssignments(student.id),
+    getTextbooks(),
+  ])
+
+  const now = new Date()
+  const pendingCount = assignments.filter((a) => a.progressStatus !== "submitted" && a.progressStatus !== "graded").length
+  const dueSoonCount = assignments.filter((a) => {
+    if (a.progressStatus === "submitted" || a.progressStatus === "graded") return false
+    if (!a.dueAt) return false
+    const due = new Date(a.dueAt)
+    const in7Days = new Date(now)
+    in7Days.setDate(in7Days.getDate() + 7)
+    return due >= now && due <= in7Days
+  }).length
+
+  const cards = [
+    {
+      title: "Courses",
+      description: "Your enrolled classes.",
+      icon: BookOpen,
+      href: "/student/learning/courses",
+      stat: `${classes.length} enrolled`,
+    },
+    {
+      title: "Assignments",
+      description: "Homework and practice.",
+      icon: PenTool,
+      href: "/student/learning/assignments",
+      stat: `${pendingCount} pending${dueSoonCount > 0 ? ` · ${dueSoonCount} due soon` : ""}`,
+    },
+    {
+      title: "Textbooks",
+      description: "Browse course materials.",
+      icon: Library,
+      href: "/student/learning/textbooks",
+      stat: `${textbooks.length} available`,
+    },
+  ]
+
+  return (
+    <div className="space-y-8">
+      <div>
+        <h2 className="text-2xl font-bold tracking-tight">My Learning</h2>
+        <p className="text-muted-foreground">Your learning hub: courses, assignments, and textbooks.</p>
+      </div>
+
+      <div className="grid gap-6 md:grid-cols-2 lg:grid-cols-3">
+        {cards.map((c) => (
+          <Link key={c.href} href={c.href}>
+            <Card className="h-full transition-all hover:shadow-md hover:border-primary/50">
+              <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
+                <CardTitle className="text-base font-medium">{c.title}</CardTitle>
+                <c.icon className="h-5 w-5 text-muted-foreground" />
+              </CardHeader>
+              <CardContent className="space-y-2">
+                <p className="text-sm text-muted-foreground">{c.description}</p>
+                <div className="flex items-center justify-between">
+                  <span className="text-sm font-medium">{c.stat}</span>
+                  <ArrowRight className="h-4 w-4 text-muted-foreground" />
+                </div>
+              </CardContent>
+            </Card>
+          </Link>
+        ))}
+      </div>
+    </div>
+  )
+}