README said 'no separate feature flag', but the build keeps FEATURE_COLIBRI
(build.cfg default YES) as an internal escape hatch (e.g. building without a
colibri checkout). Clarify: colibri is staged by default; FEATURE_COLIBRI=NO is
an internal build-time hatch, not a user-facing option. Resolves a wiki-ledger
residue item.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>