feat: add terms acceptance checkbox and validation

[sauce-base]

This pull request introduces a required "Terms of Service and Privacy Policy" acceptance checkbox to the registration process, ensuring users must explicitly agree before registering. It updates both the React and Vue registration forms, adds server-side validation and error messaging, and updates related tests to cover the new requirement. Additionally, it makes minor UI consistency improvements to login and registration links.

Registration Flow Updates:

• Added a required "Terms of Service and Privacy Policy" checkbox to both React (Register.tsx) and Vue (Register.vue) registration forms, including UI, validation, error display, and disabling the register button until all fields (including terms) are completed. [1] [2] [3] [4] [5] [6] [7] [8] [9]
• Server-side: Updated RegisterRequest.php to require the terms field to be accepted and provide a custom error message if not.

Testing Updates:

• Updated feature tests in RegisterTest.php to include the terms field and added a test to ensure terms acceptance is validated. [1] [2] [3] [4] [5]
• Updated Playwright E2E page object (RegisterPage.ts) and tests to interact with the new checkbox, verify its visibility, and ensure the register button is only enabled when all fields (including terms) are completed. [1] [2] [3] [4] [5]

UI Consistency Improvements:

• Updated login and register page links to use a consistent color and removed the faded (/70) variant for improved clarity. [1] [2] [3] [4]
• Ensured the "Forgot your password?" link does not wrap awkwardly by adding whitespace-nowrap. [1] [2]