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.

packages/db/drizzle/0000_absent_rocket_raccoon.sql

@@ -0,0 +1,23 @@
+CREATE TABLE `events` (
+	`id` text PRIMARY KEY NOT NULL,
+	`index` integer NOT NULL,
+	`type` text NOT NULL,
+	`direction` text,
+	`lane` integer NOT NULL,
+	`source` text,
+	`identity` text,
+	`occurred_at` text NOT NULL,
+	`prev_hash` text,
+	`signature` text NOT NULL
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX `events_index_unique` ON `events` (`index`);--> statement-breakpoint
+CREATE TABLE `users` (
+	`id` text PRIMARY KEY NOT NULL,
+	`username` text NOT NULL,
+	`password_hash` text NOT NULL,
+	`role` text NOT NULL,
+	`created_at` text DEFAULT (current_timestamp) NOT NULL
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX `users_username_unique` ON `users` (`username`);