Advisory registry of known adapter capabilities.
:data:KNOWN_CAPABILITIES is a frozenset of capability strings derived from the
intrinsics catalog. It is advisory only: callers are warned (not rejected) when a
capability outside this set is used, so that custom adapters and pre-release
intrinsics are not blocked.
Deriving from the catalog (rather than hand-copying) keeps the two registries in
sync automatically — adding a new entry to catalog.py automatically registers
it as a known capability.
.. note::
Capabilities are currently derived from catalog entry names. Decoupling the
capability vocabulary from entry names (an explicit capability field on
CatalogEntry) is tracked as a follow-up under Epic #929.
