feat: Add Azure OpenAI language model support and enhance README

[JustStas]

Description

Follows @HarvinderBhullar proposition in #49

• Implement AzureOpenAILanguageModel inheriting from OpenAILanguageModel
• Reuses all inference logic, only overrides client initialization
• Supports azure: and aoai: model_id prefixes (e.g., azure:gpt-4o)
• Accepts azure_endpoint, api_key, and api_version as parameters
• Auto-registered with priority 20 via registry decorator
• Add Azure OpenAI to provider documentation and examples
• Update .gitignore for cleaner temp file handling

(Feature)
Fixes #49

How Has This Been Tested?

import os
import textwrap

import langextract as lx


def main() -> None:
  prompt = textwrap.dedent("""
      Extract main characters and brief emotions from the text.
      Use exact spans from the text for extraction_text.
      """)

  examples = [
      lx.data.ExampleData(
          text=(
              "ROMEO. But soft! What light through yonder window breaks? "
              "It is the east, and Juliet is the sun."
          ),
          extractions=[
              lx.data.Extraction(
                  extraction_class="character", extraction_text="ROMEO"
              ),
              lx.data.Extraction(
                  extraction_class="emotion",
                  extraction_text="But soft!",
                  attributes={"feeling": "awe"},
              ),
          ],
      )
  ]

  input_text = (
      "Lady Juliet gazed longingly at the stars, her heart aching for Romeo"
  )

  # Built-in provider approach: Use lx.extract with azure: prefix and language_model_params
  result = lx.extract(
      text_or_documents=input_text,
      prompt_description=prompt,
      examples=examples,
      model_id="azure:gpt-5",  # Prefix selects Azure provider, deployment=gpt-4o
      fence_output=True,  # Required for Azure OpenAI (like OpenAI)
      use_schema_constraints=False,  # Required for Azure OpenAI (like OpenAI)
      language_model_params={
          "azure_endpoint": os.environ["AZURE_OPENAI_ENDPOINT"],
          "api_key": os.environ["AZURE_OPENAI_API_KEY"],
          "api_version": "2024-07-01-preview",
      },
  )

  print(result)

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.
• 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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[github-actions]

❌ Infrastructure File Protection

This PR modifies protected infrastructure files:

• .gitignore (3 changes)

Only repository maintainers are allowed to modify infrastructure files (including .github/, build configuration, and repository documentation).

Note: If these are only formatting changes, please:

1. Revert changes to .github/ files
2. Use ./autoformat.sh to format only source code directories
3. Avoid running formatters on infrastructure files

If structural changes are necessary:

1. Open an issue describing the needed infrastructure changes
2. A maintainer will review and implement the changes if approved

For more information, see our Contributing Guidelines.

[github-actions]

❌ Infrastructure File Protection

This PR modifies protected infrastructure files:

• .gitignore (3 changes)

Only repository maintainers are allowed to modify infrastructure files (including .github/, build configuration, and repository documentation).

Note: If these are only formatting changes, please:

1. Revert changes to .github/ files
2. Use ./autoformat.sh to format only source code directories
3. Avoid running formatters on infrastructure files

If structural changes are necessary:

1. Open an issue describing the needed infrastructure changes
2. A maintainer will review and implement the changes if approved

For more information, see our Contributing Guidelines.

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