db: business-layer schema — ledger/device event split, tariffs, permits, sessions

Implements the wiki design in packages/db + packages/shared.

Event split: rename events -> ledger_events (signed business ledger) and add
device_events (unsigned telemetry). ledger_events gains a signed JSON payload
(amount/tariffVersionId/sessionRef/tender…) + keyId; canonicalize() includes
the payload via sorted-key serialization so business data is tamper-evident.
Raw Dingtian input now writes device_events, not a signed input_received.

New tables: tariffs + immutable tariff_versions (composable/versioned, currency
+ FX-ready), permits (+ permit_credentials, permit_plates; maxConcurrent default
1), blocklist, sessions (rebuildable projection cache — not a source of truth).

shared: split ParkingEvent/Type into LedgerEvent/LedgerEventType + DeviceEventKind;
add LedgerPayload, Tender, TariffStructure/TariffBlock.

Regenerated a single baseline migration (no production chain data existed).
Verified: chain appends + verifyChain ok; tampering a payment payload breaks
the signature. Full repo builds (5/5).

apps/server/src/routes/events.ts

@@ -1,5 +1,5 @@
 import type { FastifyInstance } from "fastify";
-import { desc, events, type Db } from "@parking/db";
+import { desc, ledgerEvents, type Db } from "@parking/db";
 import { requireRole } from "../auth.js";
 import type { EventLog } from "../event-log.js";
 
@@ -22,7 +22,7 @@ export async function eventRoutes(
     { preHandler: guard },
     async (req) => {
       const limit = Math.min(Math.max(Number(req.query.limit) || 100, 1), 1000);
-      const rows = db.select().from(events).orderBy(desc(events.index)).limit(limit).all();
+      const rows = db.select().from(ledgerEvents).orderBy(desc(ledgerEvents.index)).limit(limit).all();
       return { events: rows };
     },
   );