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/api/chats.ts

@@ -0,0 +1,57 @@
+import { http } from "./http";
+import type { Chat, Message, MessageType } from "../chat/types";
+
+export async function getChats(): Promise<Chat[]> {
+  const { data } = await http.get<Chat[]>("/chats");
+  return data;
+}
+
+export async function createPrivateChat(memberId: number): Promise<Chat> {
+  const { data } = await http.post<Chat>("/chats", {
+    type: "private",
+    title: null,
+    member_ids: [memberId]
+  });
+  return data;
+}
+
+export async function getMessages(chatId: number, beforeId?: number): Promise<Message[]> {
+  const { data } = await http.get<Message[]>(`/messages/${chatId}`, {
+    params: {
+      limit: 50,
+      before_id: beforeId
+    }
+  });
+  return data;
+}
+
+export async function sendMessage(chatId: number, text: string, type: MessageType = "text"): Promise<Message> {
+  const { data } = await http.post<Message>("/messages", { chat_id: chatId, text, type });
+  return data;
+}
+
+export interface UploadUrlResponse {
+  upload_url: string;
+  file_url: string;
+  object_key: string;
+  expires_in: number;
+  required_headers: Record<string, string>;
+}
+
+export async function requestUploadUrl(file: File): Promise<UploadUrlResponse> {
+  const { data } = await http.post<UploadUrlResponse>("/media/upload-url", {
+    file_name: file.name,
+    file_type: file.type || "application/octet-stream",
+    file_size: file.size
+  });
+  return data;
+}
+
+export async function attachFile(messageId: number, fileUrl: string, fileType: string, fileSize: number): Promise<void> {
+  await http.post("/media/attachments", {
+    message_id: messageId,
+    file_url: fileUrl,
+    file_type: fileType,
+    file_size: fileSize
+  });
+}