fix(ui): improve onboarding page styling to match sign-in page

Add 32px card padding and reduce max-width to 420px for consistency
with the sign-in page. Add noValidate to prevent browser-native
required validation outlines on inputs.

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

ui/src/pages/OnboardingPage.tsx

@@ -43,7 +43,7 @@ export function OnboardingPage() {
   return (
     <div className={styles.page}>
       <div className={styles.wrapper}>
-        <Card>
+        <Card className={styles.card}>
           <div className={styles.inner}>
             <div className={styles.logo}>
               <img src={cameleerLogo} alt="" className={styles.logoImg} />
@@ -59,7 +59,7 @@ export function OnboardingPage() {
               </div>
             )}
 
-            <form onSubmit={handleSubmit} className={styles.form}>
+            <form onSubmit={handleSubmit} className={styles.form} noValidate>
               <FormField label="Organization name" htmlFor="onboard-name" required>
                 <Input
                   id="onboard-name"