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/contracts/src/events.ts

@@ -0,0 +1,28 @@
+import { z } from "zod";
+import { Timestamp } from "./common";
+
+/** SSE 事件信封:seq 在进程内单调递增,客户端断线后用 ?after=<seq> 补读 */
+export const EventEnvelope = z.object({
+  seq: z.number().int().nonnegative(),
+  type: z.string().min(1),
+  at: Timestamp,
+  payload: z.unknown(),
+});
+export type EventEnvelope<P = unknown> = {
+  seq: number;
+  type: string;
+  at: string;
+  payload: P;
+};
+
+/** 已知事件类型;业务事件后续按 `域.动作` 追加 */
+export const EventType = {
+  heartbeat: "system.heartbeat",
+  resync: "system.resync",
+} as const;
+export type EventType = (typeof EventType)[keyof typeof EventType];
+
+/** 心跳 payload */
+export const HeartbeatPayload = z.object({
+  role: z.string(),
+});