- Create split-screen login page with branding left (#ffed00) and form right (D-01)
- Login form has username, password, and remember-me checkbox (D-02)
- Wire header user avatar with auth store: shows user initial, dropdown with role badge and logout
- Wire sidebar footer with auth store: shows user name, role, and initial
- Add auth, header role, and admin i18n keys to both de.json and en.json
- All new UI strings use t() function (no hardcoded text)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
