Admin feature flags marked as global

Administrators could previously tweak feature flags without a clear visual indication of the blast radius, risking unintended consequences across all organizations on the instance.

The feature flags administration page now features a prominent warning callout, and the navigation label is explicitly renamed to "Global Feature Flags." This visual friction ensures administrators understand that these toggles are instance-wide.

By clearly marking these settings as global and dangerous to change, the system actively steers administrators toward safer, organization-level overrides. This prevents accidental, widespread disruptions originating from the webapp admin interface.