feat(ADR-131): HOMECORE-UI operational dashboard + BFF gateway

Complete two-tier Cognitum operator dashboard (ADR-131), served by
homecore-server at /homecore, plus the single-origin BFF gateway that
wires it to real backends.

Front-end (zero-dep vanilla TS/JS + CSS, exact Cognitum design tokens):
- All 10 panels (§4.1-4.10): dashboard, SEED fleet + detail, fleet map,
  entities (live WS subscribe_events, never polls), rooms, COGs,
  calibration wizard, events + automation builder, witness/audit, settings.
- §6 UX invariants in code: first-class provenance, prominent stale/veto/
  fragility, null(not-trained) vs withheld vs error, --mono everywhere,
  Hailo vs CPU COG distinction.
- api.js calls the gateway routes in production; mock demoted to a
  dev-only ?demo=1 fixture (no mock in prod); typed error states.
- Tests under plain node: import-graph, boot, render-smoke (22),
  interaction (3), prod-errors (13) — 5 files green; bundle ~137 KB
  (~37x smaller than HA), <2 ms/cold-render.

BFF gateway (homecore-server/src/gateway.rs, compiled + tested on Rust 1.89):
- /api/cal/* reverse-proxy to the calibration API (ADR-151).
- GET /api/homecore/rooms with the RoomState adapter (breathing->breathing_bpm,
  heartbeat:null->heart_bpm:null, injected anomaly.threshold/room_id).
- GET /api/homecore/cogs supervisor over /var/lib/cognitum/apps/.
- GET /api/homecore/appliance from /proc + TCP service probes.
- SEED-device/appliance routes return typed 503 upstream_unavailable.
- cargo test -p homecore-server = 12/12; run live (curl-verified);
  fixed a real double-v1 proxy-URL bug found during live testing.

Honest scope: W1/W2/W4/W6-appliance functional; W3/W5/W6-Hailo/federation
return typed 503 (depend on services/hardware not in this repo).

Co-Authored-By: claude-flow <ruv@ruv.net>

v2/crates/homecore-server/README.md

@@ -116,6 +116,29 @@ export RUST_LOG="homecore=debug,homecore_api=info"
 | `--db` | `HOMECORE_DB` | `sqlite::memory:` | SQLite path (`:memory:` for ephemeral) |
 | `--location-name` | `HOMECORE_LOCATION` | `Home` | Friendly name returned by `/api/config` |
 | `--no-recorder` | — | off | Disable SQLite recorder (low-resource deployments) |
+| `--ui-dir` | `HOMECORE_UI_DIR` | `<crate>/ui` | HOMECORE-UI asset dir served at `/homecore` (ADR-131); empty disables the mount |
+
+## HOMECORE-UI dashboard (ADR-131)
+
+This binary also serves the **HOMECORE-UI** — the complete operational dashboard
+for the two-tier Cognitum stack (v0 Appliance → SEEDs → ESP32 nodes) — at
+`/homecore`, alongside the HA-compat `/api` surface. It is a zero-dependency,
+no-build-step vanilla TS/JS + CSS frontend living in `ui/`:
+
+```bash
+cargo run -p homecore-server          # then open http://localhost:8123/homecore/
+```
+
+It drives the live `/api` + `/api/websocket` (`subscribe_events`) endpoints; panels
+backed by services not in this binary (SEED HTTPS API, calibration ADR-151,
+federation ADR-105) render against a DEMO-flagged contract-conformant mock until
+those endpoints land (ADR-131 §7.1). Frontend tests + benchmark run under plain
+`node` (no `npm install`):
+
+```bash
+cd ui && npm test     # import graph + render-smoke + interaction (24 checks)
+cd ui && npm run bench # bundle budget (~137 KB, ~37× smaller than HA) + render timing
+```
 
 ## Comparison to Home Assistant