Add the admin CRM panel foundation including:
- Login/logout authentication flow with CSRF protection
- Sidebar layout with navigation for all CRM modules
- Comprehensive admin.css (1680+ lines) with components for
cards, tables, badges, forms, buttons, alerts, modals,
pagination, search, responsive breakpoints, and print styles
- admin.js with sidebar toggle, confirm dialogs, auto-dismiss
alerts, and table search filtering
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
