createKeyedRegistry

Description#

Signal-based keyed registry with a destroy-safe unregister path.
Encodes the registration lifecycle contract every cngx registry must honour, so the classic teardown race is unwritable: when Angular recreates a keyed child, the successor's register can run BEFORE the predecessor's DestroyRef teardown - an unguarded unregister(key) would then evict the successor's live registration. Here unregister demands the holder instance and only removes on identity match.

Collision semantics mirror CngxErrorRegistry: registering a different value under a live key is silently absorbed (swap-is-noop) with a dev-mode warning, never an in-place swap - downstream readers keep observing the instance they resolved.

The registry is plain signals - create it as a field on the owning directive / service, no injection context required.