Redesign PlatformPlatform landing page with minimalistic approach

[tjementum]

Summary & Motivation

Redesign the landing page with a minimalistic approach to provide a cleaner, more professional first impression. The previous landing page contained multiple feature sections, community content, and technology showcases that were removed in favor of a simple welcome message encouraging users to customize the page with their own branding.

• Remove all feature sections, community section, technology sections, and CTA sections (10 component files deleted)
• Create new reusable PublicNavigation and PublicFooter components for consistent public-facing pages
• Add support for routes to opt out of AuthSyncModal via disableAuthSync context flag
• Fix tenant switching to preserve the current path after navigation (important for landing page experience)
• Change login/signup layout breakpoint from md to lg for better responsive behavior
• Update footer attribution to "Built with PlatformPlatform" with HTML comment

The new landing page displays a welcome message, navigation with login/signup buttons, theme/locale switchers, and a footer with social links. This provides a minimal starting point that downstream projects can easily customize.

Checklist

• I have added tests, or done manual regression tests
• I have updated the documentation, if necessary

[linear]

PP-625 Redesign landing page with minimalistic approach

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud