CngxMatTabsRegistry

Sibling host-directive that owns the per-MatTab handle registry for [cngxMatTabs]. Keeps the parent under the level-4 organism LOC guard and lets per-tab decoration directives reach the registry through a typed token.

Owns: contentChildren(MatTab) query, the setupsByTab map (per-tab cngx setup paired with a child EnvironmentInjector scoping the _stateChanges bridge), an effect() that diffs the MatTab list and (un)registers handles with CNGX_TAB_GROUP_HOST, and a DestroyRef cleanup that destroys every child injector.

Composition: [cngxMatTabs] declares this in hostDirectives; both share the parent's CngxTabGroupPresenter and the same <mat-tab-group> content-children scope.