Fix: LS hosted checkout URL path is /checkout/buy/<variant>

Mirror of HelpmateAI commit 8016457 (Codex P1 finding on HelpmateAI's
PR #4). The LS scaffold for both apps was built from the same
template, so the same URL bug exists here too — even though Codex
didn't flag it on AI Job Agent's PR #2 (Codex's review surfaces
sample issues rather than every instance).

Old: https://<store>.lemonsqueezy.com/buy/<variant>
New: https://<store>.lemonsqueezy.com/checkout/buy/<variant>

Per the LS docs at docs.lemonsqueezy.com/help/checkout/hosted-checkouts,
the `/buy/` path is a non-checkout endpoint. Every Pro upgrade CTA
would have resolved there and failed silently the moment LS goes
live with real variant IDs. This fix lands BEFORE KYC clears so
the broken state never reaches paid customers.

No test changes — the helper is exercised in real LS sandbox testing
which happens post-merge once variant IDs exist.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: LEANDERANTONY

frontend/src/lib/api.ts

@@ -423,7 +423,13 @@ export async function getWorkspaceQuota() {
 //
 // The hosted checkout URL pattern is documented at
 // https://docs.lemonsqueezy.com/help/checkout/hosted-checkouts.
-// Format: https://{store_subdomain}.lemonsqueezy.com/buy/{variant_uuid}
+// Format: https://{store_subdomain}.lemonsqueezy.com/checkout/buy/{variant_uuid}
+// An earlier draft used `/buy/<variant>` which is a non-checkout
+// endpoint (Codex P1 finding on HelpmateAI's PR #4, mirrored here
+// because the LS scaffold for both apps was built from the same
+// template). Paid conversion fails the moment LS goes live with the
+// wrong path, so this fix lands BEFORE KYC clears.
+//
 // We append checkout[custom][user_id] so the LS webhook can bind the
 // subscription back to our Supabase user. Without that binding the
 // webhook handler has no way to write the right row.
@@ -476,7 +482,7 @@ export function getCheckoutUrl(
       ? LEMONSQUEEZY_VARIANT_PRO
       : LEMONSQUEEZY_VARIANT_BUSINESS;
   if (!variant) return "";
-  const base = `https://${LEMONSQUEEZY_STORE_ID}.lemonsqueezy.com/buy/${variant}`;
+  const base = `https://${LEMONSQUEEZY_STORE_ID}.lemonsqueezy.com/checkout/buy/${variant}`;
   if (!userId) return base;
   // LS expects checkout fields as URL-encoded query params; the
   // bracket syntax is the documented form for nested fields.