CngxAsyncRegistry

Opt-in aggregation registry for in-flight async operations.

A single derived source for "is anything loading?" across a whole app: the shell binds one isAnythingLoading() instead of N hand-maintained flags. Producers register their CngxAsyncState (via injectAsyncState({ register: true }), the HTTP interceptor, or directly) and unregister on teardown.

Not providedIn: 'root' - consumers opt in with provideAsyncRegistry. When the registry is absent, producers skip registration entirely.

Keyed by a per-operation uid, not the human label. Async operations are transient and collide on label; uid identity keeps N concurrent same-label (or unlabeled) operations independent, so one unregister evicts exactly its own entry. This is the one deliberate divergence from CngxErrorRegistry (which keys by a stable scope name).

Both views are computed() only - no effect, no service calls. Inner status reactivity flows through each entry's CngxAsyncState signals; the Map signal's mapKeySetEqual short-circuits register/unregister churn without hiding status changes.