Bug:- websocket_base_url derivation corrupts URLs containing http:// in query params

Confirm this is an issue with the Python library and not an underlying OpenAI API
This is an issue with the Python library

Describe the bug
When no websocket_base_url is provided, the SDK derives one from base_url using Python's str.replace():

base_url.replace("https://", "wss://").replace("http://", "ws://")

str.replace() replaces all occurrences, not just the scheme prefix. If http:// appears anywhere else in the URL (query parameter, path segment, etc.), it gets incorrectly rewritten too.

To Reproduce

from openai import OpenAI

client = OpenAI(
    api_key="sk-test",
    base_url="https://proxy.com/forward?target=http://backend.internal/v1"
)
print(client.websocket_base_url)

Expected result

wss://proxy.com/forward?target=http://backend.internal/v1

Actual result

wss://proxy.com/forward?target=ws://backend.internal/v1

Suggested fix
Replace only the scheme prefix, not all occurrences:

if base_url.startswith("https://"):
    return "wss://" + base_url[len("https://"):]
elif base_url.startswith("http://"):
    return "ws://" + base_url[len("http://"):]

Environment

• Library version: latest (main)
• File: src/openai/_client.py lines ~117–119
• Python version: 3.x

Start in src/openai/_client.py around lines 117–119 and inspect how websocket_base_url is derived when no value is provided. Reproduce the issue with the proxy URL in the report, then verify the resulting URL preserves http:// in the query parameter while changing only the base scheme. Add regression coverage using the reported example and run the relevant client tests.