Append-only signed event log; persist Dingtian input pushes

Implement the core anti-fraud primitive: an append-only, hash-chained,
signed event log (the schema + types predated this; the writer/signer are new).

- EventLog (apps/server): serialized append, monotonic index, prevHash chain,
  signature; verifyChain() detects tamper/reorder/delete. No update/delete paths.
- Signer abstraction (packages/shared) over the ATECC608 secure element, with a
  SoftwareSigner (HMAC, EVENT_SIGNING_KEY) shipped now since the chip is still
  open-question #6. Documented: software signer is tamper-evident but NOT
  unforgeable-by-owner.
- Add ParkingEventType "input_received" for raw device inputs (not yet a
  vehicle_entry, which the entry flow will append later).
- Read API: GET /api/events; integrity self-check: GET /api/events/verify (admin).

Verified on hardware: shorting the Dingtian inputs produced signed, chained
input_received events; verifyChain ok; direct DB tamper/delete detected.

NOTE: the log captures host-originated actions only. Out-of-band relay
actuation (sniffed relay_pw, string protocol, ip_watchdog) produces no event
by design -- the control is reconciliation vs. an independent witness, which is
not yet built. See wiki/concepts/append-only-event-chain.md.

apps/server/src/server.ts

@@ -3,9 +3,13 @@ import jwt from "@fastify/jwt";
 import Fastify, { type FastifyInstance } from "fastify";
 import { createDb, type Db } from "@parking/db";
 import { TOKEN_COOKIE, requireJwtSecret } from "./auth.js";
+import { deviceEvents } from "./device-events.js";
+import { EventLog } from "./event-log.js";
 import { PrinterMonitor } from "./printer-monitor.js";
+import { buildSigner } from "./signer.js";
 import { authRoutes } from "./routes/auth.js";
 import { deviceRoutes } from "./routes/devices.js";
+import { eventRoutes } from "./routes/events.js";
 import { printerRoutes } from "./routes/printers.js";
 import { setupRoutes } from "./routes/setup.js";
 
@@ -59,7 +63,27 @@ export async function buildServer(opts: BuildOptions = {}): Promise<FastifyInsta
   app.addHook("onReady", async () => printerMonitor.start());
   app.addHook("onClose", async () => printerMonitor.stop());
 
-  // TODO: entry flow (input event → signed event → print → relay), event-log routes.
+  // Append-only signed event log. Subscribe device pushes (e.g. Dingtian button
+  // presses) into the hash-chained, signed `events` table — the anti-fraud audit
+  // trail. The device is NOT trusted; the host record is the source of truth, and
+  // a relay open with no matching signed event is itself the anomaly. We record
+  // the raw input faithfully as `input_received` (not yet a `vehicle_entry` — that
+  // comes with the full entry flow). See wiki/concepts/append-only-event-chain.md.
+  const eventLog = new EventLog(db, buildSigner(app.log));
+  await eventRoutes(app, db, eventLog);
+  const unsubscribeInput = deviceEvents.onInput((e) => {
+    eventLog
+      .append({
+        type: "input_received",
+        lane: 0, // lane mapping is a TODO — device->lane lookup arrives with setup/lane wiring
+        identity: `${e.driverId}:${e.deviceId} input:${e.input}/${e.edge}`,
+        occurredAt: e.at,
+      })
+      .catch((err) => app.log.error(`event-log append failed: ${(err as Error).message}`));
+  });
+  app.addHook("onClose", async () => unsubscribeInput());
+
+  // TODO: entry flow (input event → signed event → print → relay); map device→lane.
 
   return app;
 }