Add configurable network timeouts to all HTTP clients

[Deadpool2000]

ref #18
This PR introduces a simple, built-in way for developers to configure network timeouts across all the SDK clients (Client, AsyncClient, OauthClient, and AsyncOauthClient).

Why is this necessary?

Right now, the SDK uses the default 5-second timeout imposed by httpx. While that's fine for simple requests, it's a bit too strict for heavy API operations (like generating large PDFs or querying massive datasets) and causes perfectly valid requests to unexpectedly crash with a TimeoutException.

Previously, the only way to avoid this was to build a completely custom httpx.Client(timeout=...) object and pass it in during initialization, which was a lot of unnecessary boilerplate for a very common need.

How was this implemented? Let's break down the changes:

1. Added a timeout argument: I added timeout: float = 30.0 directly to the __init__ methods of all four client classes.
2. Passed it down natively: The param is passed directly into httpx.Client(timeout=timeout) and httpx.AsyncClient(timeout=timeout).
3. Smarter default: Upped the default SDK timeout from 5 seconds to a much safer 30 seconds to prevent crashes on slower endpoints without hanging forever.
4. Preserved backward compatibility: Check out the logic: self.client = client if client is not None else httpx.Client(timeout=timeout). We only apply this timeout if a user isn't passing in their own custom HTTP client config. This guarantees we don't break existing custom transport layers.
5. Updated Documentation:
   • Appended a new Configuring Network Timeouts snippet to the README.md.
   • Replicated those usage snippets to docs/readme-pypi.md and updated the Markdown API tables to reflect the new timeout=30.0 signature.

Testing

• Ran the internal test suite via poetry run pytest and verified all 18 existing test cases still pass perfectly with these changes!

[Deadpool2000]

@francescobianco check this and let me know can it be merged?

Feature #18

[francescobianco]

Very useful — let’s merge it. Thanks for your dedication! 🚀 @Deadpool2000