fix: production oauth redirect to frontend host

server/server.js

@@ -434,9 +434,25 @@ app.get('/api/auth/twitch', (req, res) => {
 app.get('/api/auth/twitch/callback', async (req, res) => {
   const { code, error } = req.query;
   
+  let frontendRedirect = '/';
+  if (process.env.NODE_ENV === 'production') {
+    if (process.env.TWITCH_REDIRECT_URI) {
+      try {
+        const redirectUrl = new URL(process.env.TWITCH_REDIRECT_URI);
+        frontendRedirect = `${redirectUrl.protocol}//${redirectUrl.host}/`;
+      } catch (e) {
+        frontendRedirect = 'https://mimic42.qzz.io/';
+      }
+    } else {
+      frontendRedirect = 'https://mimic42.qzz.io/';
+    }
+  } else {
+    frontendRedirect = 'http://localhost:5173/';
+  }
+  
   if (error) {
     console.error('Twitch OAuth error callback:', error);
-    return res.redirect('/auth-failed');
+    return res.redirect(`${frontendRedirect}auth-failed`);
   }
 
   try {
@@ -528,11 +544,6 @@ app.get('/api/auth/twitch/callback', async (req, res) => {
     };
 
     console.log(`[Auth] User ${displayName} logged in. Role: ${role}`);
-
-    // Redirect to frontend (in local dev it could redirect to port 5173, in prod to root)
-    const frontendRedirect = process.env.NODE_ENV === 'production' 
-      ? '/' 
-      : 'http://localhost:5173/';
       
     res.redirect(frontendRedirect);
   } catch (err) {