fix: Skip OAuth if already logged in, go straight to checkout

If user has existing session from Trinity Console login,
/stripe/auth now redirects directly to /stripe/checkout
instead of re-triggering Discord OAuth.

Chronicler #75

services/arbiter-3.0/src/routes/stripe.js

@@ -30,7 +30,8 @@ router.options('/create-checkout-session', cors(corsOptions));
 /**
  * STRIPE AUTH - Entry point from website
  * GET /stripe/auth?tier=X
- * Stores tier in session, redirects to Discord OAuth
+ * If already logged in, goes straight to checkout
+ * If not, stores tier in session and redirects to Discord OAuth
  */
 router.get('/auth', (req, res) => {
   const tierLevel = req.query.tier;
@@ -39,6 +40,11 @@ router.get('/auth', (req, res) => {
     return res.status(400).send('Invalid tier level. Please return to the subscribe page and try again.');
   }
   
+  // If user is already authenticated, skip OAuth and go straight to checkout
+  if (req.user && req.user.id) {
+    return res.redirect(`/stripe/checkout?tier=${tierLevel}`);
+  }
+  
   // Store tier in session for after OAuth callback
   req.session.pendingCheckoutTier = parseInt(tierLevel);