Reserved: application-layer (use-case) sources for the consensus context.
The orphan demo use case application_consensus_validate_block was removed
(Law 8 — subtraction before addition; zero production callers). This
directory is kept as the documented hexagonal "application layer" scaffold
(see Makefile APPLICATION_CONTEXTS) so the next real use case has a home,
exactly as app/events/ is kept reserved-and-empty by design.
