Feature/ab#32465 model endpoint configuration management

[jacobwillsmith]

Pull request overview

Updated the OpenAI configuration shape so the runtime reads the standard nested Azure:... keys directly. This keeps appsettings and environment-variable binding aligned with normal .NET configuration behavior and removes the need for explicit compatibility constants.

Changes:

• Simplified OpenAI config resolution to read Azure:OpenAI:ApiKey and Azure:OpenAI:Endpoint directly
• Removed the explicit compatibility constants for the raw OpenAI env-var names
• Preserved the legacy Azure:OpenAI:ApiUrl fallback path
• Updated the development appsettings override to match the current branch state
• Kept the rest of the OpenAI runtime behavior unchanged

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

🧪 Unit Test Results (Parallel Execution)

📊 Summary

Result	Count
✅ Passed	620
❌ Failed	0
⚠️ Skipped	0

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