feat(auth-ui): build custom auth pages in the shared design system

[ibourgeois]

Goal

Replace default auth presentation with custom Blade and Livewire pages built from the shared component system.

Scope

• Login page
• Forgot password page
• Reset password page
• Confirm password page if required by the Fortify flow

Out of Scope

• Registration pages
• Profile management pages

Acceptance Criteria

• Auth pages use the shared shell-adjacent design language and components
• Required Fortify flows are available through the custom pages
• The pages support light and dark mode

Dependencies

• Depends on feat(ui): create the first branded Blade component set #6, feat(auth): install Fortify and wire backend authentication flows #7, and feat(users): split user name fields and add computed attributes #8

Test Plan

• Add feature tests for auth page responses and form submissions
• Manually verify page rendering and flow completion