Inject the resolved editor registry. Sugar over
inject(CNGX_FILTER_EDITORS). Exists so consumers can read editors
without importing the token directly when they already inject other
filter-builder helpers (e.g. inside a slot directive context).
Snapshot semantics. The returned ReadonlyMap is captured at
injection time. Runtime swaps of CNGX_FILTER_EDITORS in nested DI
scopes are NOT observed by an already-injected consumer. If a
consumer needs reactive editor swap behaviour, re-inject() the
token at the swap-boundary's injector instead of cached references.