Resident memory of the engine process (upstream voicebox#901 / #923).

VoiceLabs: admin-gated and on its OWN path rather than folded into /health on purpose. /health is a shared producer/consumer contract — the storefront parses it — so adding a field there is schema drift; and process memory is operator information, not something an anonymous caller on api.voicelabs.now should be able to read.

available: false means the platform does not publish RSS (the desktop build), NOT that the process is using nothing.