[tosind]

The development sign-in page now explains that it is for local use and lets contributors choose a seeded admin, teacher, or student account. Selecting a role fills the editable email field; entering a different email clears the role selection. Teacher remains the default.

The layout uses freeCodeCamp's existing colors, typography, and form controls. Native radio buttons provide keyboard navigation, the role choices stack on phones, and the email field has its own label and help text. Native POST submission, callback handling, production gating, and the Auth0 redirect/retry flow are preserved. The README describes the new account picker.

Before	After

Phone screenshots

Before	After

Validation:

• pnpm run lint passed (existing repository warnings remain).
• pnpm test: 332 tests passed, including component coverage for role selection, custom emails, errors, callbacks, and Auth0 behavior.
• Playwright: all eight smoke tests passed, including arrow-key role selection and inspection of the native custom-email POST and callback.
• Inspected at 1280px and 390px; verified no horizontal overflow at 320px.
• pnpm run build passed.

Related to #640, section 4: redesign the development sign-in page. This PR addresses that item only.

Checklist:

• I have read and followed the contribution guidelines.
• This pull request targets main.
• I have run pnpm run lint and pnpm test locally.
• I have tested these changes in the browser with pnpm run develop.

AI assistance was used for implementation and review; all checks listed above were run locally.