Initial project setup with multi-component architecture

- Initialize TypeScript project with pnpm
- Create agent, gateway, client, and shared modules
- Configure ESM with strict TypeScript settings

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/shared/index.ts

@@ -0,0 +1 @@
+export * from "./types.js";

src/shared/types.ts

@@ -0,0 +1,5 @@
+export interface Message {
+  id: string;
+  payload: unknown;
+  timestamp: number;
+}