Clear "already subscribed" newsletter error on next interaction

Matches standard form-validation behavior: any further edit to the
email or consent checkbox after the already-subscribed message
appears now dismisses it, instead of leaving it stuck until submit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/lib/useNewsletterSignup.ts

@@ -27,15 +27,34 @@ export function useNewsletterSignup(source: NewsletterOptInSource) {
   const [error, setError] = useState("");
   const emailRef = useRef<HTMLInputElement>(null);
 
+  // Clears a previous submit-time error (real failure or "already
+  // subscribed") the moment the customer interacts with the form again —
+  // same "stale validation message shouldn't linger" behavior
+  // emailError already had for itself, extended to the submit-result
+  // error too, since it's otherwise easy to misread as still describing
+  // the current (possibly already-corrected) input.
+  function clearSubmitError() {
+    if (status === "error") {
+      setStatus("idle");
+      setError("");
+    }
+  }
+
   function handleEmailChange(value: string) {
     setEmail(value);
     if (emailError) setEmailError("");
+    clearSubmitError();
   }
 
   function handleEmailBlur(value: string) {
     setEmailError(validateEmailFormat(value));
   }
 
+  function handleConsentChange(checked: boolean) {
+    setConsent(checked);
+    clearSubmitError();
+  }
+
   async function handleSubmit(e: FormEvent<HTMLFormElement>) {
     e.preventDefault();
     const formatError = validateEmailFormat(email);
@@ -70,5 +89,5 @@ export function useNewsletterSignup(source: NewsletterOptInSource) {
     }
   }
 
-  return { email, emailError, consent, setConsent, status, error, successMessage: SUCCESS_MESSAGE, emailRef, handleEmailChange, handleEmailBlur, handleSubmit };
+  return { email, emailError, consent, handleConsentChange, status, error, successMessage: SUCCESS_MESSAGE, emailRef, handleEmailChange, handleEmailBlur, handleSubmit };
 }