sync: add aichat MCP server from Docs OpenAPI spec

[Copilot]

The upstream Docs updated the aichat service spec, but no aichat/ MCP server existed in this monorepo. This PR bootstraps the full server implementation synced to openapi/aichat.json.

New: aichat/ MCP server

Models (core/types.py)

ChatModel Literal covering all 70+ models from the spec:

• GPT-5 series (gpt-5.5, gpt-5.5-pro, gpt-5.4, …)
• GPT-4 series (gpt-4.1, gpt-4o, gpt-4o-search-preview, …)
• o-series (o1, o3, o4-mini, and dated/effort variants)
• Third-party: deepseek-r1, deepseek-r1-0528, deepseek-v3, deepseek-v3-250324, grok-3, glm-5.1…glm-3-turbo

Tools (tools/)

• aichat_conversation — maps to POST /aichat/conversations; exposes all schema fields: question, model, id (as conversation_id), stateful, preset, references
• aichat_list_models / aichat_get_usage_guide — info tools

Infrastructure

• core/client.py — async httpx client targeting /aichat/conversations
• core/config.py — AICHAT_REQUEST_TIMEOUT env var (default 60s)
• Full OAuth 2.1 support for remote HTTP mode (shared pattern)
• pyproject.toml, Dockerfile, smithery.yaml, server.json, etc.

sync.yaml

aichat:
  repo: AceDataCloud/AIChatMCP
  exclude:
    - .gitbooks