refs https://github.com/TryGhost/Product/issues/3745
---
This pull request adds a new feature to the `admin-x-settings` app that
allows users to customize the colors of their email newsletters. It also
simplifies and refactors the routing logic and the components related to
integrations, newsletters, and users. It introduces new dependencies and
components for color manipulation and selection, and updates the
existing components and stories to use them.
refs https://github.com/TryGhost/Product/issues/3751
---
This pull request adds limit checks and upgrade prompts for various
features in the admin-x-settings app, such as staff, members,
newsletters, custom integrations, and custom themes. It uses a custom
hook called `useLimiter`, which relies on the `@tryghost/limit-service`
package and the host settings configuration data.
refs https://github.com/TryGhost/Product/issues/3729
---
This pull request enhances the custom integrations feature in the
admin-x-settings app by adding accessibility and UI improvements to the
`Select` and `WebhookModal` components, refactoring the webhook and
integration types in the API module, and adding a new end-to-end test
file to verify the functionality using mocked API responses.
