Add AI Chat Orchestration to call APIs

# Why?

**As a** user

**I want** to be able to write out a prompt and have AI interpret what I want to do

**So that** I can more easily call APIs

# What?

Implement LangChain, with whatever OpenAI model is free.

https://js.langchain.com/docs/how_to/tool_calling

# Additional context

Can just call APIs directly from library.
Ideally, the chat will confirm with the user before making a API call.

Don't want AI to directly manipulate the database. Want to have at least the APIs to constrain what it's able to do.

該 issue 提到要實作 LangChain，用於編排 AI 聊天以呼叫 APIs。首先檢查專案現有的 API 結構，以及目前已有的任何 AI 或聊天整合。查閱 LangChain 關於 tool calling 的文件，了解如何設定一個能夠解析 prompts 並在發起 API 呼叫前確認操作的 agent。目標是新增一個與 OpenAI 模型和現有 API 層介接的新 service 或 module，並確保它不會直接操作資料庫。

由索引模型根據 Issue 內容生成。