fix(auth): restrict seeded credentials exclusively to super admin and demo student in backend and api documentation

backend/main.py

@@ -125,7 +125,11 @@ def login(payload: LoginPayload, session: Session = Depends(get_session)):
     
     # Allow demo/admin mock logic to still work if needed
     if payload.email == "demo@pragativeer.com" and payload.password == "Pv9#kL2$mQ8!vX4@":
-        demo_user = session.exec(select(models.User).where(models.User.email == "student@pragativeer.com")).first()
+        demo_user = session.exec(select(models.User).where((models.User.email == "demo@pragativeer.com") | (models.User.email == "student@pragativeer.com"))).first()
+        if demo_user and demo_user.email != "demo@pragativeer.com":
+            demo_user.email = "demo@pragativeer.com"
+            session.add(demo_user)
+            session.commit()
         token_id = str(demo_user.id) if demo_user else "b0e17378-864d-439e-8806-708dc48a891b"
         return {"success": True, "role": "user", "token": token_id}
     if payload.email == "admin@pragativeer.com" and payload.password == "admin123":