Operators can now disable specific pages (Dashboard, Nodes, Advertisements,
Messages, Map, Members, Pages) via FEATURE_* environment variables. Disabled
features are fully hidden: removed from navigation, return 404 on routes,
and excluded from sitemap/robots.txt. Dashboard auto-disables when all of
Nodes/Advertisements/Messages are off. Map auto-disables when Nodes is off.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
