Fix Azure OpenAI base URL construction

The base URL was incorrectly using a forward slash (/) instead of a dot (.) to construct the Azure OpenAI endpoint, resulting in malformed URLs like `https://{resourceName}/openai.azure.com` instead of the correct `https://{resourceName}.openai.azure.com`.

This caused DNS resolution failures when attempting to connect to Azure OpenAI services.

Reference: https://learn.microsoft.com/en-us/azure/ai-services/openai/reference

Fixes #139

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: jamesrochabrun

Sources/OpenAI/Azure/DefaultOpenAIAzureService.swift

@@ -22,7 +22,7 @@ public final class DefaultOpenAIAzureService: OpenAIService {
     self.httpClient = httpClient
     self.decoder = decoder
     openAIEnvironment = OpenAIEnvironment(
-      baseURL: "https://\(azureConfiguration.resourceName)/openai.azure.com",
+      baseURL: "https://\(azureConfiguration.resourceName).openai.azure.com",
       proxyPath: nil,
       version: nil)
     apiKey = azureConfiguration.openAIAPIKey