Function all_supported 

pub fn all_supported() -> Catalogue

Returns the full Catalogue of algorithms russh advertises plus the flags gitway list-algorithms needs to render the operator- facing view.

The list is sourced from russh’s named constants (e.g. russh::kex::CURVE25519, russh::cipher::CHACHA20_POLY1305). New algorithms a future russh release adds will appear here on the next anvil-ssh bump.

is_default is true iff the entry is in the matching anvil_default_*() list; denylisted is true iff is_denylisted returns true. An algorithm cannot be both — the curated defaults are denylist-clean by construction.