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.

packages/devices/src/registry.ts

@@ -27,8 +27,19 @@ export interface ConfigField {
   readonly help?: string;
 }
 
+/** A JSON-serializable config value. Mostly flat scalars (host, port, credentials),
+ *  but some configs carry nested structure — e.g. an access controller's
+ *  `relays: [{ relay, direction, button? }]` map. See entry-exit-points.md. */
+export type ConfigValue =
+  | string
+  | number
+  | boolean
+  | null
+  | ConfigValue[]
+  | { [k: string]: ConfigValue };
+
 /** Opaque per-instance config the admin fills in (host, port, credentials…). */
-export type DeviceConfig = Record<string, string | number | boolean>;
+export type DeviceConfig = Record<string, ConfigValue>;
 
 /**
  * A driver: metadata describing a supported device model/family, the config