Add a batch of counts, and the device's relayed events, for the signing device

Carries the device header with a person's session, or the daemon's own device credential (a device route); device_id in the body must be that device. Counts add to the day's row and are deltas since the last accepted post. events are what the daemon and the client say happened: each carries a name from a closed list and a time, optionally a session_id (a UUIDv7) and properties, a closed set of keys per name; the raw archive's two carry a closed reason. An event whose name this service does not know, a property its name does not have and a value outside its enum are dropped, never refused: the rest of the batch is accepted. A batch empty of both counts and events is a 400.