Captures the centered-card registration design 1:1 from the claude.ai/design export. Covers all 10 sections: desktop overview, header, above-card copy, form fields, password states, notification card, submit button, success panel, mobile layout, and i18n/a11y/backend implementation notes. Relates to #269 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>