Adds display name validation, terms_version, locale sync trigger and pgTAP tests (KTO-01 criteria 1, 2, 10, 11). Includes GoTrue spike results. Refs #1 Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>