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/hooks/useRealtime.ts

@@ -0,0 +1,60 @@
+import { useEffect, useMemo, useRef } from "react";
+import { useAuthStore } from "../store/authStore";
+import { useChatStore } from "../store/chatStore";
+import type { Message } from "../chat/types";
+import { buildWsUrl } from "../utils/ws";
+
+interface RealtimeEnvelope {
+  event: string;
+  payload: Record<string, unknown>;
+  timestamp: string;
+}
+
+export function useRealtime() {
+  const accessToken = useAuthStore((s) => s.accessToken);
+  const me = useAuthStore((s) => s.me);
+  const prependMessage = useChatStore((s) => s.prependMessage);
+  const typingByChat = useRef<Record<number, Set<number>>>({});
+
+  const wsUrl = useMemo(() => {
+    return accessToken ? buildWsUrl(accessToken) : null;
+  }, [accessToken]);
+
+  useEffect(() => {
+    if (!wsUrl) {
+      return;
+    }
+    const ws = new WebSocket(wsUrl);
+
+    ws.onmessage = (messageEvent) => {
+      const event: RealtimeEnvelope = JSON.parse(messageEvent.data);
+      if (event.event === "receive_message") {
+        const chatId = Number(event.payload.chat_id);
+        const message = event.payload.message as Message;
+        prependMessage(chatId, message);
+      }
+      if (event.event === "typing_start") {
+        const chatId = Number(event.payload.chat_id);
+        const userId = Number(event.payload.user_id);
+        if (userId === me?.id) {
+          return;
+        }
+        if (!typingByChat.current[chatId]) {
+          typingByChat.current[chatId] = new Set<number>();
+        }
+        typingByChat.current[chatId].add(userId);
+        useChatStore.getState().setTypingUsers(chatId, [...typingByChat.current[chatId]]);
+      }
+      if (event.event === "typing_stop") {
+        const chatId = Number(event.payload.chat_id);
+        const userId = Number(event.payload.user_id);
+        typingByChat.current[chatId]?.delete(userId);
+        useChatStore.getState().setTypingUsers(chatId, [...(typingByChat.current[chatId] ?? [])]);
+      }
+    };
+
+    return () => ws.close();
+  }, [wsUrl, prependMessage, me?.id]);
+
+  return null;
+}