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/snapshots.ts

@@ -0,0 +1,49 @@
+import type { FastifyInstance } from "fastify";
+import { desc, eq, snapshots, type Db } from "@parking/db";
+import { requireRole } from "../auth.js";
+
+// Read access to captured entry/exit snapshots (the BLOB-in-DB image store, see
+// packages/db schema + wiki/concepts/lane-direction.md). Snapshots are evidence
+// tied to a signed vehicle_entry/exit by `identity`; the operator reviews them
+// next to the event. Read-only — images are written only by the flows (snapshot.ts),
+// never via the API.
+
+export async function snapshotRoutes(app: FastifyInstance, db: Db): Promise<void> {
+  const guard = requireRole("admin", "operator", "cashier", "readonly");
+
+  // Snapshot metadata for one session/credential identity (NOT the bytes), newest
+  // first — lets the UI show "entry/exit image" links beside an event.
+  app.get<{ Params: { identity: string } }>(
+    "/api/snapshots/by-identity/:identity",
+    { preHandler: guard },
+    async (req) => {
+      const rows = db
+        .select({
+          id: snapshots.id,
+          direction: snapshots.direction,
+          deviceId: snapshots.deviceId,
+          identity: snapshots.identity,
+          contentType: snapshots.contentType,
+          capturedAt: snapshots.capturedAt,
+        })
+        .from(snapshots)
+        .where(eq(snapshots.identity, req.params.identity))
+        .orderBy(desc(snapshots.capturedAt))
+        .all();
+      return { snapshots: rows };
+    },
+  );
+
+  // Stream one snapshot's image bytes by id. Returns the stored content type.
+  app.get<{ Params: { id: string } }>(
+    "/api/snapshots/:id",
+    { preHandler: guard },
+    async (req, reply) => {
+      const row = db.select().from(snapshots).where(eq(snapshots.id, req.params.id)).get();
+      if (!row) return reply.code(404).send({ error: "no such snapshot" });
+      reply.header("content-type", row.contentType);
+      reply.header("cache-control", "private, max-age=31536000, immutable");
+      return reply.send(row.bytes);
+    },
+  );
+}