feat: add Astraflow provider support

[ucloudnb666]

Summary

Adds Astraflow by UCloud as an OpenAI-compatible LLM provider alongside the existing OpenAI models.

Astraflow is an OpenAI-compatible AI model aggregation platform supporting 200+ models, available via a global endpoint and a China endpoint. Because it is API-compatible with OpenAI, integration requires only setting base_url + api_key on ChatOpenAI — no new SDK or subpackage needed.

Changes

.env.example

• Documents ASTRAFLOW_API_KEY (global endpoint) and ASTRAFLOW_CN_API_KEY (China endpoint).

app/core/config.py

• Reads ASTRAFLOW_API_KEY, ASTRAFLOW_CN_API_KEY, ASTRAFLOW_BASE_URL, and ASTRAFLOW_CN_BASE_URL from the environment, with the official default base URLs pre-filled.

app/services/llm/registry.py

• Adds two Astraflow entries to LLMRegistry.LLMS:
  • astraflow/default — global endpoint, uses ASTRAFLOW_API_KEY
  • astraflow-cn/default — China endpoint, uses ASTRAFLOW_CN_API_KEY
• Both entries reuse ChatOpenAI (already a dependency) with the Astraflow base_url so no new packages are required.
• The get() method already supports per-call overrides, so any Astraflow model slug can be passed at call-time via kwargs.

Usage

# .env
ASTRAFLOW_API_KEY=your-global-key
DEFAULT_LLM_MODEL=astraflow/default

Or for the China endpoint:

ASTRAFLOW_CN_API_KEY=your-cn-key
DEFAULT_LLM_MODEL=astraflow-cn/default

Sign up at https://astraflow.ucloud-global.com (global) or https://astraflow.ucloud.cn (China).