Initial scaffold: Turborepo monorepo + design wiki

Turborepo (pnpm workspaces) with all dependencies pinned to latest
mutually-compatible versions: turbo 2.9, TypeScript 6, Fastify 5,
React 19, Vite 8, better-sqlite3 12 + Drizzle ORM 0.45.

Layout:
- apps/server   Fastify backend (local JWT auth + role guard, /health)
- apps/web      React 19 + Vite 8 operator SPA
- packages/db   Drizzle schema on SQLite/WAL; append-only events + users
- packages/devices  reader/printer/relay adapter interfaces (intent-only relay)
- packages/shared   shared domain types

Architecture constraints from the design wiki are encoded in the scaffold:
append-only hash-chained + signed event log, device-agnostic adapters,
"a barrier is not a door" (relay expresses intent only), fully-local
offline-first auth.

wiki/ is an LLM-maintained Obsidian knowledge base (28 pages) ingested
from the architecture & design notes, with its own maintenance schema.

Verified: pnpm install, full turbo build (5/5), server boots and serves
/health, drizzle-kit generates the initial migration.

wiki/concepts/device-adapter-pattern.md

@@ -0,0 +1,32 @@
+---
+type: concept
+tags: [parking, architecture, devices]
+sources: [parking-system-architecture]
+updated: 2026-06-14
+---
+
+# Device-Adapter Pattern
+
+How the system stays **device-agnostic**: business logic talks **only to interfaces, never to a
+device SDK**. Each physical device is an adapter implementing one interface; **swapping hardware
+means writing a new adapter and nothing else changes.** Implemented as isolated [[fastify]]
+plugins emitting onto a shared internal event bus. (See [[parking-system-architecture]] §5.)
+
+```ts
+interface CardReaderDevice {
+  connect(): Promise<void>
+  onCardRead(cb: (cardNumber: string, door: number) => void): void
+  disconnect(): Promise<void>
+}
+interface PrinterDevice {
+  printTicket(data: TicketData): Promise<void>
+  checkStatus(): Promise<'ready' | 'offline' | 'paper_out'>
+}
+interface RelayDevice {
+  pulseOpen(doorId: number): Promise<void>   // intent only — see safety note
+  getDoorStatus(doorId: number): Promise<'open' | 'closed'>
+}
+```
+
+Note the `RelayDevice` expresses **intent only** — see the [[barrier-not-a-door]] safety
+principle. The choice of *which* adapter to trust is the [[trust-boundary]] decision.