Add Multilanguage Support to the Unsubscribe Management Page

Currently, STOQ's unsubscribe management page (dash.stoqapp.com) only supports English, regardless of the configured multi-language settings.

Requested enhancement:

• Support multiple languages on the unsubscribe management page, including Japanese.

• Translate all customer-facing text, including unsubscribe options and confirmation messages.

• Automatically display the appropriate language based on the customer's locale or the language used in their notification email.

Expected outcome: Customers should be able to manage their back-in-stock subscriptions and unsubscribe in their preferred language, ensuring a consistent, localized experience.