Add Access Gate for Required Groups on ExApp HTTP traffic.

AppAPI cannot restrict ExApps by Nextcloud group; enforce any-of membership in-library with Wrap/Check, deploy-env helpers, and positive-only cache.

Co-authored-by: Cursor <cursoragent@cursor.com>

doc.go

@@ -1,3 +1,3 @@
-// Package gonexapp provides AppAPI credentials, OCS JSON calls, and ExApp user
-// preferences for Nextcloud ExApp Services.
+// Package gonexapp provides AppAPI credentials, OCS JSON calls, ExApp user
+// preferences, and an optional Required Groups Access Gate for Nextcloud ExApp Services.
 package gonexapp