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]>

apps/server/src/worker/index.ts

@@ -0,0 +1,30 @@
+import { EventType } from "@umt/contracts";
+import type { Logger } from "pino";
+import type { EventBus } from "../http/sse";
+
+export interface WorkerDeps {
+  logger: Logger;
+  heartbeatMs: number;
+  /** role=all 时与 API 共享同一总线,心跳可在 SSE 中看到 */
+  bus?: EventBus;
+}
+
+/** worker 占位:只打印心跳。持久任务引擎在 W1(packages/tasks)接入 */
+export function startWorker({ logger, heartbeatMs, bus }: WorkerDeps) {
+  const log = logger.child({ component: "worker" });
+  let n = 0;
+  const beat = () => {
+    n += 1;
+    log.debug({ n }, "worker heartbeat");
+    bus?.publish(EventType.heartbeat, { role: "worker", n });
+  };
+  log.info({ heartbeatMs }, "worker started");
+  beat();
+  const timer = setInterval(beat, heartbeatMs);
+  return {
+    async stop() {
+      clearInterval(timer);
+      log.info("worker stopped");
+    },
+  };
+}