Agent login token endpoint for programmatic authentication

Features

• Agent login token endpoint for programmatic authentication
• Hidden free plan with 500 emails per month and 3 mailboxes
• Mobile navigation with full-screen overlay for public pages
• Dynamic Open Graph images and SEO improvements
• Portal sidebar layout improvements

Fixes

• Fixed Domain Connect hostname validation for security
• Fixed SSR compatibility for portal navigation
• Fixed full-page navigation for docs and skill reference routes