Migrate from deprecated AzureOpenAI to OpenAI client constructors

[Copilot]

This PR migrates the repository from the deprecated Azure-specific OpenAI client constructors (AsyncAzureOpenAI) to the standard OpenAI constructors (AsyncOpenAI) to maintain compatibility with current and future OpenAI SDK versions.

Changes Made

Core Client Migration (src/quartapp/chat.py):

• Replaced openai.AsyncAzureOpenAI() with openai.AsyncOpenAI()
• Changed parameter mapping:
  • azure_endpoint → base_url (with "/openai/v1" suffix for Azure OpenAI compatibility)
  • azure_ad_token_provider → api_key
• Removed the deprecated api_version parameter completely

Infrastructure Updates:

• Removed AZURE_OPENAI_API_VERSION environment variable references from all Bicep files (infra/main.bicep, infra/aca.bicep)
• Updated deployment parameters (infra/main.parameters.json)
• Cleaned up GitHub Actions workflow (.github/workflows/azure-dev.yaml)
• Updated environment sample file (.env.sample)

Dependency Requirements:

• Updated src/pyproject.toml to enforce openai>=1.108.1 (the minimum version supporting this migration)

Test Updates:

• Modified test assertions to validate the new client properties (api_key, base_url) instead of Azure-specific attributes
• Updated test assertions to expect the "/openai/v1" suffix in base_url
• Removed obsolete AZURE_OPENAI_VERSION environment variables from test setup

Authentication Compatibility

The migration maintains full compatibility with both authentication patterns:

API Key Authentication:

# Before: AsyncAzureOpenAI(api_key="...", azure_endpoint="...", api_version="...")
# After: AsyncOpenAI(api_key="...", base_url="..."/openai/v1")

Managed Identity Authentication:

# Before: AsyncAzureOpenAI(azure_ad_token_provider=token_provider, azure_endpoint="...", api_version="...")
# After: AsyncOpenAI(api_key=token_provider, base_url="..."/openai/v1")

All tests continue to pass (6/6), ensuring no functional regressions while adopting the supported SDK API surface.

Fixes #61.

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[pamelafox]

@copilot This needs to have "/openai/v1" at end of the URL

[Copilot]

Added "/openai/v1" suffix to the Azure OpenAI endpoint URL. The base_url now correctly appends "/openai/v1" to the AZURE_OPENAI_ENDPOINT environment variable value. Also updated the test assertions to expect this suffix. Changes in commit fa1f8ea.

[pamelafox]

See comment