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/challenge-response-auth.md

@@ -0,0 +1,29 @@
+---
+type: concept
+tags: [parking, security, crypto, access-control]
+sources: [parking-system-architecture]
+updated: 2026-06-14
+---
+
+# Challenge–Response Auth (asymmetric signatures)
+
+The authentication scheme for the [[esp32-custom-controller]]. Closes the actual hole in the
+[[uhppote-udp-protocol]]: **forged or replayed commands**. The requirement is **authenticity +
+freshness (anti-replay)**; encryption is optional. (See [[parking-system-architecture]] §7.)
+
+```
+Host (private key)                    ESP32 (host's PUBLIC key only)
+  │── "open lane 2" ──────────────────▶│ generates fresh random nonce
+  │◀──────────── nonce ─────────────────│
+  │ sign(nonce ‖ command ‖ ts) ────────▶│ verify vs stored public key
+  │                                     │ check nonce fresh + unused → pulse relay
+```
+
+## The elegant property
+
+The controller stores **only a public key**. Physically compromising the ESP32 (popping the
+cabinet, dumping flash via the [[atecc608]]) yields **nothing usable for forging commands**. The
+fresh per-command **nonce** defeats replay without counter-persistence headaches.
+
+A shared-secret / encrypted channel would **not** have this property — the secret would sit on
+both ends. That's why authentication (not encryption) is the right build here.