feat(ontology): declare the build's features, and record what the rename closed

A capability is per-platform and also per-build: `simon ai models` exists
only where `vault` was enabled, so an agent that knows the platform and not
the feature set still cannot tell what this binary does.
`capability::enabled_features` reports it from `cfg!`, describing the running
artefact rather than the manifest, and
`reported_features_match_the_commands_the_binary_accepts` checks a feature
reported as on brought its command with it.

HANDOFF's queued-breaking section now records that item 1 is done and what it
cost to have deferred it: the rename turned up three live defects the
misleading name had been hiding, making five from this one pattern over three
discoveries. Worth reading before deferring the next "cosmetic" change.

Item 2 stays open with its reasoning made explicit. Every reader now either
produces a real swap number or errors, so the ambiguity is unreachable
through any of them, but the type still permits it. 62 read sites; deferred
on cost, not on doubt.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>