devices: pool-of-spaces model — drop lane, per-relay direction

A parking lot is one pool of spaces with a flexible set of entry/exit
points — no "lane". Direction is a property of each RELAY inside an access
controller; readers/cameras bind to a controller relay and inherit it.

Schema:
- drop `lane` from ledger_events, device_events, sessions
- rename lane_devices -> devices (no lane/direction columns)
- access config.relays=[{relay,direction,button?}]; reader/camera
  config.controllerId+relay binding
- fresh 0000_baseline migration (history reset; dev data was throwaway)

Signed ledger:
- remove `lane` from canonicalize(); bump signer keyId sw-hmac-v1 -> v2
  (v1 events won't verify under v2 — intentional, gated per-event by keyId)

Server:
- new device-resolve.ts (replaces lane-map.ts): relayForButton,
  relayForDevice, firstRelayByDirection, devicesByDirection
- entry-flow: button terminal -> its relay; exit/permit: reader's bound
  relay; dispatcher resolves the bound relay + inherited direction
- camera snapshots fire by direction site-wide, async, never block open
- DeviceConfig widened to nested JSON for relays[]

Web:
- wizard: no lane selector; add controllers (relay map + entry-button
  terminal) first, then bind readers/cameras/printers to a controller relay

Wiki: new entry-exit-points.md (replaces lane-direction); reworked
entry-exit-readers, parking-session, first-run-setup, device-registry,
append-only-event-chain, device-events; removed stale lane/LaneMap mentions.

wiki/concepts/entry-exit-readers.md

@@ -38,6 +38,10 @@ There are **two populations** of users, and they map to **two integration paths*
   keeps autonomy + native event log.
 - **Both models can share one relay** (valid Wiegand read **or** host `open` in "controlled"
   mode), so one lane serves permit + casual.
+- **Each reader BINDS to a controller relay** (`config.controllerId` + `relay`) — the barrier it
+  sits at — and inherits that relay's direction (entry/exit/both). An exit read opens exactly that
+  relay; an entry read the entry relay. This is how separate in/out readers are disambiguated, with
+  no "lane". See [[entry-exit-points]].
 - **Host-in-the-loop is good for fraud detection** — two independent records (host's signed
   [[append-only-event-chain]] entry + the UHPPOTE remote-open event) should reconcile 1:1; any
   mismatch is an anomaly.