Preserve nil timeouts through request transport

[fallintoplace]

Summary

• preserve timeout: nil as "no timeout" instead of coercing it to 0.0
• skip deadline and x-stainless-timeout handling when a request disables timeouts
• reset pooled Net::HTTP socket timeouts and add regressions for default and per-request nil timeout behavior

Why

The README documents timeout: nil as disabling timeouts, but the transport currently calls to_f on the timeout value. In Ruby, nil.to_f becomes 0.0, which turns the computed deadline into "right now" rather than removing the deadline.

Validation

• ASDF_RUBY_VERSION=3.4.9 asdf exec bundle exec ruby -Itest test/openai/client_test.rb --name=/timeout/
• ASDF_RUBY_VERSION=3.4.9 asdf exec bundle exec ruby -Itest test/openai/client_test.rb

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 28a082a4b6

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Preserve nil timeout while waiting for pooled connections

When timeout: nil is used and all connections for an origin are checked out, calling pool.with without an explicit timeout falls back to connection_pool's default checkout timeout (5 seconds). That means a request that disabled timeouts can still raise a timeout while queued for a pooled connection, even though README says queue time counts toward the request timeout and nil disables it.

Useful? React with 👍 / 👎.