Add web client and containerized deployment stack

Web client:

- Added React + TypeScript + Vite + Tailwind application in web/.

- Implemented auth, chat list, chat messages, typing indicators, file uploads, and voice recording/playback.

- Added typed API layer, Zustand stores, and realtime websocket hook integration.

Containerization:

- Added backend Dockerfile and project .dockerignore.

- Added web multi-stage Dockerfile with nginx static hosting and API/WS reverse proxy.

- Added full docker-compose stack with postgres, redis, minio, backend, worker, mailpit, and web.

- Added MinIO bucket bootstrap init job and updated README with Docker quick-start.

web/src/utils/ws.ts

@@ -0,0 +1,8 @@
+export function buildWsUrl(token: string): string {
+  const explicit = import.meta.env.VITE_WS_URL;
+  if (explicit) {
+    return `${explicit}?token=${encodeURIComponent(token)}`;
+  }
+  const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
+  return `${protocol}//${window.location.host}/api/v1/realtime/ws?token=${encodeURIComponent(token)}`;
+}