CngxDialogDefaults

App-wide dialog defaults, populated via provideDialogConfig in the root providers (or provideDialogConfigAt in a component's viewProviders for a sub-tree scope).

Distinct from CngxDialogConfig, which is the per-open option bag passed to CngxDialogOpener.open(). This one carries defaults for every dialog in the scope; that one configures a single dialog instance.

Only labels today. Size / backdrop / close-on-escape / focus-fallback defaults are deliberately absent - no consumer has asked for them, and a key with no caller is configuration for its own sake.