feat(dashboard): optimize teacher dashboard ui and layout

- Refactor layout: move Needs Grading to main column, Homework to sidebar
- Enhance TeacherStats: replace static counts with actionable metrics (Needs Grading, Active Assignments, Avg Score, Submission Rate)
- Update RecentSubmissions: table view with quick grade actions and late status
- Update TeacherSchedule: vertical timeline view with scroll hints
- Update TeacherHomeworkCard: compact list view
- Integrate Recharts: add TeacherGradeTrends chart and shared chart component
- Update documentation

src/modules/dashboard/components/teacher-dashboard/teacher-dashboard-header.tsx

@@ -1,11 +1,22 @@
 import { TeacherQuickActions } from "./teacher-quick-actions"
 
-export function TeacherDashboardHeader() {
+interface TeacherDashboardHeaderProps {
+  teacherName: string
+}
+
+export function TeacherDashboardHeader({ teacherName }: TeacherDashboardHeaderProps) {
+  const today = new Date().toLocaleDateString("en-US", {
+    weekday: "long",
+    year: "numeric",
+    month: "long",
+    day: "numeric",
+  })
+
   return (
     <div className="flex flex-col justify-between space-y-4 md:flex-row md:items-center md:space-y-0">
       <div>
-        <h2 className="text-2xl font-bold tracking-tight">Teacher</h2>
-        <p className="text-muted-foreground">Overview of today&apos;s work and your classes.</p>
+        <h2 className="text-2xl font-bold tracking-tight">Good morning, {teacherName}</h2>
+        <p className="text-muted-foreground">It&apos;s {today}. Here&apos;s your daily overview.</p>
       </div>
       <TeacherQuickActions />
     </div>