Add Azure OpenAI Custom Model Integration (#1001)

Fixes #710 

This PR implements comprehensive Azure OpenAI integration for Dyad,
enabling users to leverage Azure
OpenAI models through proper environment variable configuration. The
implementation adds Azure as a
supported provider with full integration into the existing language
model architecture, including support
  for GPT-5 models. Key features include environment-based
configuration using `AZURE_API_KEY` and `AZURE_RESOURCE_NAME`,
specialized UI components that provide clear
setup instructions and status indicators, and seamless integration with
Dyad's existing provider system.
The Azure provider leverages the @ai-sdk/azure package (v1.3.25) for
compatibility with the current
  TypeScript language model interfaces.

The implementation includes robust error handling for missing
configuration, comprehensive test coverage
with 9 new unit tests covering critical functionality like model client
creation and error scenarios, and
  an E2E test for the Azure-specific settings UI. 

<img width="1510" height="908" alt="Screenshot 2025-08-18 at 9 14 32 PM"
src="https://github.com/user-attachments/assets/04aa99e1-1590-4bb0-86c9-a67b97bc7500"
/>

---------

Co-authored-by: graphite-app[bot] <96075541+graphite-app[bot]@users.noreply.github.com>
Co-authored-by: Will Chen <willchen90@gmail.com>

e2e-tests/azure_provider_settings.spec.ts

@@ -0,0 +1,43 @@
+import { expect } from "@playwright/test";
+import { test as testWithPo } from "./helpers/test_helper";
+
+testWithPo("Azure provider settings UI", async ({ po }) => {
+  await po.setUp();
+  await po.goToSettingsTab();
+
+  // Look for Azure OpenAI in the provider list
+  await expect(po.page.getByText("Azure OpenAI")).toBeVisible();
+
+  // Navigate to Azure provider settings
+  await po.page.getByText("Azure OpenAI").click();
+
+  // Wait for Azure settings page to load
+  await po.page.waitForSelector('h1:has-text("Configure Azure OpenAI")', {
+    state: "visible",
+    timeout: 5000,
+  });
+
+  // Check that Azure-specific UI is displayed
+  await expect(po.page.getByText("Azure OpenAI Configuration")).toBeVisible();
+  await expect(po.page.getByText("AZURE_API_KEY")).toBeVisible();
+  await expect(po.page.getByText("AZURE_RESOURCE_NAME")).toBeVisible();
+
+  // Check environment variable status indicators exist
+  await expect(
+    po.page.getByText("Environment Variables Configuration"),
+  ).toBeVisible();
+
+  // Check setup instructions are present
+  await expect(po.page.getByText("How to configure:")).toBeVisible();
+  await expect(
+    po.page.getByText("Get your API key from the Azure portal"),
+  ).toBeVisible();
+  await expect(po.page.getByText("Find your resource name")).toBeVisible();
+  await expect(
+    po.page.getByText("Set these environment variables before starting Dyad"),
+  ).toBeVisible();
+
+  // Check that status indicators show "Not Set" (since no env vars are configured in test)
+  const statusElements = po.page.locator(".bg-red-100, .bg-red-800\\/20");
+  await expect(statusElements.first()).toBeVisible();
+});