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.

apps/server/src/routes/devices.ts

@@ -1,5 +1,5 @@
 import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
-import { eq, laneDevices, type Db } from "@parking/db";
+import { eq, devices, type Db } from "@parking/db";
 import { deviceEvents } from "../device-events.js";
 import { verifyDigest } from "../digest-auth.js";
 
@@ -36,7 +36,7 @@ export async function deviceRoutes(app: FastifyInstance, db: Db): Promise<void>
   const handle = async (req: FastifyRequest<{ Params: InputParams }>, reply: FastifyReply) => {
     const { deviceId, n, edge } = req.params;
 
-    const row = await db.select().from(laneDevices).where(eq(laneDevices.id, deviceId)).get();
+    const row = await db.select().from(devices).where(eq(devices.id, deviceId)).get();
     const cfg = row?.config as DingtianDeviceConfig | undefined;
 
     // Unknown device / not a dingtian / no push creds / wrong source IP → 404.