chore: scaffold monorepo and migrate uhd_web design system (W0-A)

- pnpm workspace: apps/{web,server}, packages/{contracts,db,domain,adapters,tasks,agent,testkit}
- server: Hono + zod-openapi, API Key auth with scopes, redacting pino logger, SSE event bus with replay, worker heartbeat
- db: Kysely + pg, file migrator, 0001_init (settings/api_key/audit_event/outbox_event)
- web: React Router 7 SPA console shell with 12 workspace placeholders, uhd_web tokens/ui/guard scripts
- docs: ADR-001 (Node over Deno), dev runbook, design system rules

Co-Authored-By: Claude Fable 5.1 <[email protected]>

packages/db/src/client.ts

@@ -0,0 +1,17 @@
+import { Kysely, PostgresDialect } from "kysely";
+import pg from "pg";
+import type { DB } from "./types";
+
+export interface CreateDbOptions {
+  /** 默认读 process.env.DATABASE_URL */
+  connectionString?: string;
+  max?: number;
+}
+
+/** 创建带连接池的 Kysely 实例;调用方负责在退出时 db.destroy() */
+export function createDb(opts: CreateDbOptions = {}): Kysely<DB> {
+  const connectionString = opts.connectionString ?? process.env.DATABASE_URL;
+  if (!connectionString) throw new Error("DATABASE_URL 未设置");
+  const pool = new pg.Pool({ connectionString, max: opts.max ?? 10 });
+  return new Kysely<DB>({ dialect: new PostgresDialect({ pool }) });
+}