Phase 2 of the edge + control-plane architecture. A per-team local stack
can now mirror its state UP to a central instance so judges get a fleet
view — outbound-only, so it works from behind the room NAT.
Central ingest (same api/, central-mode):
- POST /instances/register + /instances/:id/heartbeat (fleet-secret
gated) + an `instances` table and GET /instances (admin) fleet read.
- PUT /teams/:id and POST /submissions accept an optional `site` tag;
`site` column added to teams + submissions (grouping/filtering).
- WS snapshot now carries instances; instance:update broadcast added.
Reporter sidecar (deploy/lan/reporter/, opt-in `federated` compose
profile): subscribes to the local WS feed and replays team/submission
writes up to central, namespaced by SITE_ID (ids never collide) and
site-tagged. Registers + heartbeats; failed writes queue in an in-memory
outbox and backfill on reconnect. Proven end-to-end (local→reporter→
central) before commit.
Also fixes a latent bug: listSubmissions selected snake_case columns but
mapped camelCase, so GET /submissions summaries were missing teamId/
teamName/submittedAt. Aliased the columns; added a regression assertion.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
