- GET /topologies/services/{name}/schema serves the declared ServiceConfigField
metadata so the Inspector can auto-render forms.
- PUT /(topologies/{id}/)deckies/{decky}/services/{svc}/config persists the
validated dict (DB + compose); container untouched (Save).
- POST /(topologies/{id}/)deckies/{decky}/services/{svc}/apply persists then
force-recreates <decky>-<svc> so the new env takes effect (Apply, destructive).
- New engine helper update_service_config wires both fleet and topology paths
through the existing _persist_fleet_change / _rerender_topology_compose
machinery; emits decky.<name>.service_config_changed on the bus.