registerRemoteConfigProvider

Registers a Remote Config source after initialize. Safe to call late -- unlike feature flags, providers here are read on demand rather than snapshotted at startup, so there is no race with a dashboard that already read an earlier list. Returns false if the runtime is disabled or CaptureCategory.STATE is off.

Abstract, not defaulted, like every other member here: the compiler refusing to build a facade that misses a member is what guarantees full/no-op parity (see NoopFacadeProviderContractTest). A default would let the no-op facade silently inherit "registered nothing" for a capture-gated method instead of stating it deliberately.