ADD: added basic backend function plus a mockup for a cli interface

frontend/studia/src/utils/jwt.tsx

@@ -0,0 +1,23 @@
+// utils/jwt.ts
+import { jwtDecode } from 'jwt-decode';
+
+export interface TokenPayload {
+  userId: string;
+  email: string;
+  role: string[];
+  exp: number;
+}
+
+export function getUserFromToken(token: string): TokenPayload | null {
+  try {
+    const decoded = jwtDecode<TokenPayload>(token);
+    if (decoded.exp && decoded.exp < Date.now() / 1000) {
+      console.warn("Token ist abgelaufen");
+      return null;
+    }
+    return decoded;
+  } catch (error) {
+    console.error("Fehler beim Decodieren des Tokens:", error);
+    return null;
+  }
+}