feat: add support for GitHub Models provider

- Introduced environment variable CLAUDE_CODE_USE_GITHUB to enable GitHub Models.
- Added checks for GITHUB_TOKEN or GH_TOKEN for authentication.
- Updated base URL handling to include GitHub Models default.
- Enhanced provider detection and error handling for GitHub Models.
- Updated relevant functions and components to accommodate the new provider.

src/services/github/deviceFlow.test.ts

@@ -0,0 +1,94 @@
+import { afterEach, describe, expect, mock, test } from 'bun:test'
+
+import {
+  GitHubDeviceFlowError,
+  pollAccessToken,
+  requestDeviceCode,
+} from './deviceFlow.js'
+
+describe('requestDeviceCode', () => {
+  const originalFetch = globalThis.fetch
+
+  afterEach(() => {
+    globalThis.fetch = originalFetch
+  })
+
+  test('parses successful device code response', async () => {
+    globalThis.fetch = mock(() =>
+      Promise.resolve(
+        new Response(
+          JSON.stringify({
+            device_code: 'abc',
+            user_code: 'ABCD-1234',
+            verification_uri: 'https://github.com/login/device',
+            expires_in: 600,
+            interval: 5,
+          }),
+          { status: 200 },
+        ),
+      ),
+    )
+
+    const r = await requestDeviceCode({
+      clientId: 'test-client',
+      fetchImpl: globalThis.fetch,
+    })
+    expect(r.device_code).toBe('abc')
+    expect(r.user_code).toBe('ABCD-1234')
+    expect(r.verification_uri).toBe('https://github.com/login/device')
+    expect(r.expires_in).toBe(600)
+    expect(r.interval).toBe(5)
+  })
+
+  test('throws on HTTP error', async () => {
+    globalThis.fetch = mock(() =>
+      Promise.resolve(new Response('bad', { status: 500 })),
+    )
+    await expect(
+      requestDeviceCode({ clientId: 'x', fetchImpl: globalThis.fetch }),
+    ).rejects.toThrow(GitHubDeviceFlowError)
+  })
+})
+
+describe('pollAccessToken', () => {
+  const originalFetch = globalThis.fetch
+
+  afterEach(() => {
+    globalThis.fetch = originalFetch
+  })
+
+  test('returns token when GitHub responds with access_token immediately', async () => {
+    let calls = 0
+    globalThis.fetch = mock(() => {
+      calls++
+      return Promise.resolve(
+        new Response(JSON.stringify({ access_token: 'tok-xyz' }), {
+          status: 200,
+        }),
+      )
+    })
+
+    const token = await pollAccessToken('dev-code', {
+      clientId: 'cid',
+      fetchImpl: globalThis.fetch,
+    })
+    expect(token).toBe('tok-xyz')
+    expect(calls).toBe(1)
+  })
+
+  test('throws on access_denied', async () => {
+    globalThis.fetch = mock(() =>
+      Promise.resolve(
+        new Response(JSON.stringify({ error: 'access_denied' }), {
+          status: 200,
+        }),
+      ),
+    )
+    await expect(
+      pollAccessToken('dc', {
+        clientId: 'c',
+        fetchImpl: globalThis.fetch,
+      }),
+    ).rejects.toThrow(/denied/)
+  })
+})