Reverts a4e65df. The maintainer prefers the more fluid model where registry
apps flow into the App Center grid as 'Available — Add' cards alongside
installed/local apps, rather than a separate /apps/marketplace destination.
Restores the Stage-4 merged-grid behaviour (loadApps merges
registry_catalog.json; createAppCard renders registry cards; addRegistryApp
dispatches app_add). The make_app.sh featured passthrough + the generator's
featured/source fields go with it (unused by the merged grid).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: librelad <librelad@digitalangels.vip>
cfb3a4f755