Make it easier to set base_url for API clients

[uezo]

Enable routing API clients through a custom proxy by setting base_url

This change allows API clients like OpenAI and Anthropic to easily configure their base_url to route requests through a specified proxy server. This simplifies the integration of various services through a unified proxy endpoint, offering better control over API traffic and network architecture.

Examples:

• For OpenAI client:

client = openai.Client(
    api_key="YOUR_API_KEY",
    base_url="http://127.0.0.1:8000/openai"
)

• For Anthropic client:

client = Anthropic(
    api_key="YOUR_API_KEY",
    base_url="http://127.0.0.1:8000/anthropic"
)