Migrate from deprecated AzureOpenAI to standard OpenAI client constructors

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This PR migrates the codebase from deprecated AsyncAzureOpenAI constructors to the standard AsyncOpenAI constructors to maintain compatibility with current OpenAI SDK versions.

Changes Made

Core Migration

• Replaced constructor: Changed openai.AsyncAzureOpenAI() to openai.AsyncOpenAI() in src/quartapp/chat.py
• Updated parameter mapping:
  • azure_endpoint → base_url
  • azure_ad_token_provider → api_key (for managed identity authentication)
  • Removed deprecated api_version parameter

Environment & Infrastructure Cleanup

• Removed AZURE_OPENAI_API_VERSION from .env.sample
• Removed openAiApiVersion parameter and related references from infra/main.bicep
• Removed AZURE_OPENAI_API_VERSION environment variable from infra/aca.bicep
• Updated dependency constraint to openai>=1.0.0 in src/pyproject.toml

Test Updates

• Updated test assertions to work with standard AsyncOpenAI client structure
• Removed obsolete AZURE_OPENAI_VERSION environment variable usage in tests
• All configuration tests continue to pass

Verified Configurations

The migration maintains full compatibility with all supported OpenAI configurations:

• Azure OpenAI with API Key: Uses base_url and api_key parameters
• Azure OpenAI with Managed Identity: Uses bearer token provider as api_key
• OpenAI.com with Key Vault: Retrieves API key from Azure Key Vault
• Local OpenAI-compatible endpoints: Works with Ollama and similar services

Benefits

• Uses supported OpenAI SDK API surface (no deprecated constructors)
• Forward-compatible with future OpenAI SDK updates
• Cleaner configuration without unnecessary API version parameters
• Zero breaking changes for end users

The application now uses the standard OpenAI client interface while maintaining all existing functionality for Azure OpenAI, OpenAI.com, and local endpoint configurations.

Fixes #104.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• aka.ms
  • Triggering command: bicep build infra/main.bicep --outfile /tmp/main.json (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
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