Connect a Shopify store with a custom-app Admin token

Token-paste alternative to the OAuth flow: connect a store using the Admin API access token of a custom app the merchant created in their own Shopify admin (Settings → Apps and sales channels → Develop apps, with the read_content/write_content scopes). Use this when the one-click OAuth connect is unavailable or when your users prefer not to install a third-party app on their store. The token is validated against the store before anything is saved; custom-app tokens do not expire. Connecting the same profile to a store again replaces the stored token in place.