POST /deckies/deploy now branches on DECNET_MODE + enrolled host presence:
when the caller is a master with at least one reachable swarm host, round-
robin host_uuids are assigned over new deckies and the config is dispatched
via AgentClient. Falls back to local docker-compose otherwise.
Extracts the dispatch loop from api_deploy_swarm into dispatch_decnet_config
so both endpoints share the same shard/dispatch/persist path. Adds
GET /system/deployment-mode for the UI to show 'will shard across N hosts'
vs 'will deploy locally' before the operator clicks deploy.
_schemas.py was a local exception to the codebase convention. The rest
of the app keeps all API request/response DTOs in decnet/web/db/models.py
alongside UserResponse, DeployIniRequest, etc. — the swarm endpoints now
follow the same convention (SwarmEnrollRequest, SwarmHostView, etc).
Deletes decnet/web/router/swarm/_schemas.py.
Splits the three grouped router files into eight api_<verb>_<resource>.py
modules under decnet/web/router/swarm/ to match the convention used by
router/fleet/ and router/config/. Shared request/response models live in
_schemas.py. Keeps each endpoint easy to locate and modify without
stepping on siblings.
