- Registration form on login page (tab toggle login/register) - POST /api/auth/register — creates account with phone+name+password - Phone mask +7 (XXX) XXX-XX-XX on login and profile pages - Username now editable in profile (latin/digits/_, 3-30 chars) - PUT /api/auth/me now accepts username with uniqueness validation Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>