fix(checkout): redirect to Stripe instead of skipping to /success

[swetalin-10]

Fixes #321

Root cause

handleCheckout() in Navbar.jsx received data.url (the Stripe-hosted checkout URL) from the backend but never used it. Instead it called navigate('/success') directly, so:

• No Stripe payment page was shown
• The user's card was never charged
• checkout.session.completed webhook never fired → no stock deduction, no order record

Fix

FRONTEND/src/components/ui/Navbar.jsx — 2-line change:

- emptyCart();
  onClose();
- navigate("/success");
+ window.location.href = data.url;

window.location.href performs a full navigation to the Stripe-hosted checkout page. After the customer pays, Stripe redirects them to /success?session_id=..., which fires the webhook for fulfillment.

emptyCart() is removed from the checkout handler because SuccessPage already calls it on mount via its own useEffect — clearing the cart before payment was confirmed was also incorrect behaviour.

Flow after this fix

User clicks "Proceed to Checkout"
  → POST /api/checkout  →  Stripe session created, URL returned
  → window.location.href = data.url
  → User completes payment on Stripe
  → Stripe redirects to /success?session_id=...
  → Stripe webhook fires → stock deducted, Order document created
  → SuccessPage mounts → emptyCart()

[vercel]

@swetalin-10 is attempting to deploy a commit to the niharika-mente's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Aamod-Dev]

Looks good, approved!