Route OpenAI o-series and gpt-3.5 model IDs to the OpenAI provider

[rahul188]

Description

OPENAI_PATTERNS in langextract/providers/patterns.py only enumerates the gpt-4* / gpt-5* families, so valid OpenAI model IDs from the reasoning line (o1, o3, o3-mini, o4-mini) and the legacy gpt-3.5-turbo family match no pattern and router.resolve raises InferenceConfigError, even though OpenAILanguageModel can serve them.

This adds two patterns:

• ^gpt-3\.5 — the gpt-3.5-turbo family
• ^o[1-9] — the o-series reasoning models; the required digit keeps other o-prefixed IDs (e.g. openchat) falling through to the unregistered-model error as before, and it does not collide with any built-in Ollama/Gemini pattern

The new test resolves o1, o3-mini, o4-mini, gpt-3.5-turbo (and gpt-4o as a guard against regressions) to OpenAILanguageModel, and asserts openchat still raises InferenceConfigError so the o-series pattern can't over-match.

Fixes #492

Bug fix

How Has This Been Tested?

$ python -m pytest tests/registry_test.py -q
15 passed, 12 subtests passed

$ python -m pytest tests -q -m "not live_api and not requires_pip" --ignore=tests/test_live_api.py
707 passed, 5 skipped, 1 deselected

The new test was run against unmodified main first and fails there on exactly the four uncovered model IDs (SUBFAILED for o1, o3-mini, o4-mini, gpt-3.5-turbo; gpt-4o passes), and passes with the fix. pyink, isort, and pylint are clean on the changed files.

Checklist:

• I have read and acknowledged Google's Open Source
  Code of conduct.
• I have read the
  Contributing
  page, and I either signed the Google
  Individual CLA
  or am covered by my company's
  Corporate CLA.
• I have discussed my proposed solution with code owners in the linked
  issue(s) and we have agreed upon the general approach. (The change follows
  the fix suggested in Bug: OpenAI o-series (o1/o3/o4-mini) and gpt-3.5 model IDs route to no provider #492; happy to adjust if the owners prefer a different
  pattern set.)
• I have made any needed documentation changes, or noted in the linked
  issue(s) that documentation elsewhere needs updating.
• I have added tests, or I have ensured existing tests cover the changes
• I have followed
  Google's Python Style Guide
  and ran pylint over the affected code.

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