feat: QA fixes, new APIs (assignments, rubrics, custom exams), Generation page enhancements

- Fix ELAI video generation (correct render endpoint, script splitting for 60s limit)
- Fix speaking script generation error handling and empty response display
- Add custom exam list API (GET /api/exam/custom/list)
- Add assignments REST API (list, create, get)
- Add rubrics REST API (list, create)
- Enhance Generation page: dynamic exam structures, auto-module selection, preview dialog, audio player
- Improve submit feedback with exam ID and status in toast notifications
- Fix ExamsListPage to show both custom exams and exam sessions
- Connect RubricsPage to backend API with fallback data
- Add Dockerfile, docker-compose.yml, requirements.txt for deployment
- Fix placement, grading, scoring, and auth controllers
- Add ErrorBoundary component for frontend resilience
- Add QA report and credentials documentation

Made-with: Cursor

frontend/src/components/ErrorBoundary.tsx

@@ -0,0 +1,62 @@
+import { Component, type ErrorInfo, type ReactNode } from "react";
+
+interface Props {
+  children: ReactNode;
+  fallback?: ReactNode;
+}
+
+interface State {
+  hasError: boolean;
+  error: Error | null;
+}
+
+export class ErrorBoundary extends Component<Props, State> {
+  constructor(props: Props) {
+    super(props);
+    this.state = { hasError: false, error: null };
+  }
+
+  static getDerivedStateFromError(error: Error): State {
+    return { hasError: true, error };
+  }
+
+  componentDidCatch(error: Error, errorInfo: ErrorInfo) {
+    console.error("ErrorBoundary caught:", error, errorInfo);
+  }
+
+  render() {
+    if (this.state.hasError) {
+      if (this.props.fallback) return this.props.fallback;
+
+      return (
+        <div className="min-h-screen flex items-center justify-center bg-background p-6">
+          <div className="max-w-md w-full text-center space-y-4">
+            <div className="mx-auto h-16 w-16 rounded-full bg-destructive/10 flex items-center justify-center">
+              <svg className="h-8 w-8 text-destructive" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                <path strokeLinecap="round" strokeLinejoin="round" d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-2.5L13.732 4c-.77-.833-1.964-.833-2.732 0L4.082 16.5c-.77.833.192 2.5 1.732 2.5z" />
+              </svg>
+            </div>
+            <h2 className="text-xl font-semibold">Something went wrong</h2>
+            <p className="text-muted-foreground text-sm">
+              An unexpected error occurred. Please try refreshing the page.
+            </p>
+            {this.state.error && (
+              <details className="text-left text-xs text-muted-foreground bg-muted rounded-lg p-3">
+                <summary className="cursor-pointer font-medium">Error details</summary>
+                <pre className="mt-2 whitespace-pre-wrap break-words">{this.state.error.message}</pre>
+              </details>
+            )}
+            <button
+              onClick={() => window.location.reload()}
+              className="inline-flex items-center justify-center rounded-md bg-primary px-4 py-2 text-sm font-medium text-primary-foreground hover:bg-primary/90"
+            >
+              Refresh Page
+            </button>
+          </div>
+        </div>
+      );
+    }
+
+    return this.props.children;
+  }
+}