fix(auth): redirect to appUrl after invite callback

origin lacks /ims basePath; use NEXT_PUBLIC_APP_URL instead.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BzvzV91UqHZKM9P58qtvrA

app/api/auth/callback/route.ts

@@ -3,18 +3,19 @@ import { createClient } from '@/lib/supabase/server'
 import { NextResponse } from 'next/server'
 
 export async function GET(request: Request) {
-  const { searchParams, origin } = new URL(request.url)
+  const { searchParams } = new URL(request.url)
   const code = searchParams.get('code')
   const nextRaw = searchParams.get('next') ?? '/'
   const next = nextRaw.startsWith('/') && !nextRaw.startsWith('//') ? nextRaw : '/'
+  const appUrl = (process.env.NEXT_PUBLIC_APP_URL ?? '').replace(/\/$/, '')
 
   if (code) {
     const supabase = await createClient()
     const { error } = await supabase.auth.exchangeCodeForSession(code)
     if (!error) {
-      return NextResponse.redirect(`${origin}${next}`)
+      return NextResponse.redirect(`${appUrl}${next}`)
     }
   }
 
-  return NextResponse.redirect(`${origin}/login?error=auth_callback_failed`)
+  return NextResponse.redirect(`${appUrl}/login?error=auth_callback_failed`)
 }