fix: auto-close signup modal when autoconfirm is enabled

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

calcpad-web/src/auth/AuthModal.tsx

@@ -26,6 +26,9 @@ export function AuthModal({ onClose, renewalMode = false }: AuthModalProps) {
       const result = await auth.signUp(email, password)
       if (result.error) {
         setError(result.error)
+      } else if (result.autoConfirmed) {
+        // Auto-confirmed — user is already signed in
+        onClose()
       } else {
         setSignupSuccess(true)
       }

calcpad-web/src/auth/AuthProvider.tsx

@@ -62,11 +62,19 @@ export function AuthProvider({ children }: { children: ReactNode }) {
   }, [])
 
   const signUp = useCallback(async (email: string, password: string) => {
-    if (!supabase) return { error: 'Supabase not configured' }
+    if (!supabase) return { error: 'Supabase not configured', autoConfirmed: false }
 
-    const { error } = await supabase.auth.signUp({ email, password })
-    if (error) return { error: error.message }
-    return { error: null }
+    const { data, error } = await supabase.auth.signUp({ email, password })
+    if (error) return { error: error.message, autoConfirmed: false }
+
+    // If session exists, user was auto-confirmed (GOTRUE_MAILER_AUTOCONFIRM=true)
+    const autoConfirmed = !!data.session
+    if (autoConfirmed && data.user) {
+      await recordPasswordAuth(data.user.id)
+      setNeedsPasswordRenewal(false)
+    }
+
+    return { error: null, autoConfirmed }
   }, [])
 
   const signIn = useCallback(async (email: string, password: string) => {