feat: add complete EnCoach frontend application

Full React 18 + TypeScript + Vite frontend with:
- 90+ pages (admin, student, teacher, public)
- shadcn/ui component library with 50+ components
- JWT authentication with role-based access control
- TanStack React Query for server state management
- 30+ API service modules
- AI-powered features (coaching, grading, generation)
- Adaptive learning UI (diagnostics, proficiency, plans)
- Institutional LMS management (courses, batches, timetable)
- Communication suite (discussions, announcements, DMs)
- Full CRUD with validation and confirmation dialogs

Made-with: Cursor

src/components/ui/collapsible.tsx

@@ -0,0 +1,9 @@
+import * as CollapsiblePrimitive from "@radix-ui/react-collapsible";
+
+const Collapsible = CollapsiblePrimitive.Root;
+
+const CollapsibleTrigger = CollapsiblePrimitive.CollapsibleTrigger;
+
+const CollapsibleContent = CollapsiblePrimitive.CollapsibleContent;
+
+export { Collapsible, CollapsibleTrigger, CollapsibleContent };