chore: import upstream snapshot with attribution

apps/sim/app/(auth)/components/auth-submit-button.tsx

@@ -0,0 +1,48 @@
+import type { ReactNode } from 'react'
+import { Chip, Loader } from '@sim/emcn'
+import { AUTH_BUTTON_CLASS } from '@/app/(auth)/components/constants'
+
+interface AuthSubmitButtonProps {
+  children: ReactNode
+  /** Label shown beside the spinner while the action is in flight. */
+  loadingLabel: string
+  loading?: boolean
+  disabled?: boolean
+  type?: 'submit' | 'button'
+  onClick?: () => void
+}
+
+/**
+ * The canonical full-width primary auth action — a `primary`-variant {@link Chip}
+ * with the shared in-flight spinner, so the primary CTA chrome lives in
+ * exactly one place.
+ */
+export function AuthSubmitButton({
+  children,
+  loadingLabel,
+  loading = false,
+  disabled = false,
+  type = 'submit',
+  onClick,
+}: AuthSubmitButtonProps) {
+  return (
+    <Chip
+      variant='primary'
+      type={type}
+      onClick={onClick}
+      disabled={disabled || loading}
+      fullWidth
+      flush
+      className={AUTH_BUTTON_CLASS}
+    >
+      {loading ? (
+        <span className='flex items-center gap-2'>
+          <Loader className='size-4' animate />
+          {loadingLabel}
+        </span>
+      ) : (
+        children
+      )}
+    </Chip>
+  )
+}