Create admin dashboard page for EuPlătesc accounts

[GabrielMajeri]

We need a zone in the admin interface to manage the EuPlătesc accounts associated with the app. The index page could have the route /admin/euplatesc-accounts. It will allow admins to view, create, update and delete EuPlătesc accounts.

The page should use something like TanStack Query to fetch and cache data (preferably in a paginated manner) and TanStack Table to display it in a tabular/list format.

The data table could have the following columns:

• ID
• Account name (a human-readable name we assign to it)
• Merchant ID
• Actions (view/edit/delete)

The description and secret key associated with the account will only be visible on a separate page, after the admin clicks on the "view" button for the respective account. The secret key should be displayed in a password input, and shown in plain text only after the user clicks on a button.

When editing the account, it should be possible to change its name, description, merchant ID or secret key.

Deleting an EuPlătesc account should produce an error if it is still associated to the global didactic_career_premium_euplatesc_account_id setting or to a faculty / student dorm.