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/device-adapter-pattern.md

@@ -33,6 +33,6 @@ principle. The choice of *which* adapter to trust is the [[trust-boundary]] deci
 
 > **In practice** the adapters are made *selectable*: a [[device-registry]] catalogs the
 > supported drivers (ZKTeco / ESP32 relay, Wiegand / TCP-IP readers, Hikvision / Dahua cameras),
-> and the admin assigns one per lane during [[first-run-setup]]. Adding hardware support = one
+> and the admin assigns instances during [[first-run-setup]]. Adding hardware support = one
 > more registered driver, no business-logic change. (The implemented interfaces add a
 > `CameraDevice` for entry/exit snapshots alongside reader/relay/printer.)