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/modules/dashboard/components/student-dashboard/student-grades-card.tsx

@@ -2,7 +2,7 @@
 
 import Link from "next/link"
 import { BarChart3 } from "lucide-react"
-import { useTranslations } from "next-intl"
+import { useTranslations, useLocale } from "next-intl"
 
 import { Button } from "@/shared/components/ui/button"
 import { ChartCardShell } from "@/shared/components/charts/chart-card-shell"
@@ -13,6 +13,7 @@ import type { StudentDashboardGradeProps } from "@/modules/homework/types"
 
 export function StudentGradesCard({ grades }: { grades: StudentDashboardGradeProps }) {
   const t = useTranslations("dashboard")
+  const locale = useLocale()
   const hasGradeTrend = grades.trend.length > 0
   const hasRecentGrades = grades.recent.length > 0
 
@@ -20,7 +21,7 @@ export function StudentGradesCard({ grades }: { grades: StudentDashboardGradePro
     title: item.assignmentTitle,
     score: Math.round(item.percentage),
     fullTitle: item.assignmentTitle,
-    submittedAt: formatDate(item.submittedAt),
+    submittedAt: formatDate(item.submittedAt, locale),
     rawScore: item.score,
     maxScore: item.maxScore,
   }))
@@ -102,7 +103,7 @@ export function StudentGradesCard({ grades }: { grades: StudentDashboardGradePro
                     <TableCell className="tabular-nums">
                       {r.score}/{r.maxScore} <span className="text-muted-foreground">({Math.round(r.percentage)}%)</span>
                     </TableCell>
-                    <TableCell className="text-muted-foreground">{formatDate(r.submittedAt)}</TableCell>
+                    <TableCell className="text-muted-foreground">{formatDate(r.submittedAt, locale)}</TableCell>
                   </TableRow>
                 ))}
               </TableBody>