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/web/app/routes/console/agent.tsx

@@ -0,0 +1,31 @@
+import { Bot, Send } from "lucide-react";
+import { EmptyState } from "~/components/console/empty-state";
+import { PageHeader } from "~/components/console/page-header";
+import { Button } from "~/components/ui/button";
+import { Input } from "~/components/ui/input";
+
+/** Agent 会话页占位:消息流 + 输入框骨架,W2/W3 接入 agent_run 与 SSE 增量 */
+export default function AgentSession() {
+  return (
+    <>
+      <PageHeader
+        title="Agent 会话"
+        description="交代目标，Agent 在授权范围内边执行边汇报；只要方案时，它只调查不执行。"
+      />
+      <div className="flex min-h-[60vh] flex-col gap-4">
+        <EmptyState
+          icon={Bot}
+          title="还没有会话"
+          description="例如：“把某部电影的 1080p 收进来”。会话能力计划在 W2 接入。"
+          className="flex-1"
+        />
+        <form className="flex items-center gap-2" onSubmit={(e) => e.preventDefault()}>
+          <Input disabled placeholder="Agent 尚未接入" className="flex-1" />
+          <Button type="submit" disabled size="icon" aria-label="发送">
+            <Send className="h-4 w-4" />
+          </Button>
+        </form>
+      </div>
+    </>
+  );
+}