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/utils/githubModelsCredentials.ts

@@ -0,0 +1,73 @@
+import { isBareMode, isEnvTruthy } from './envUtils.js'
+import { getSecureStorage } from './secureStorage/index.js'
+
+/** JSON key in the shared OpenClaude secure storage blob. */
+export const GITHUB_MODELS_STORAGE_KEY = 'githubModels' as const
+
+export type GithubModelsCredentialBlob = {
+  accessToken: string
+}
+
+export function readGithubModelsToken(): string | undefined {
+  if (isBareMode()) return undefined
+  try {
+    const data = getSecureStorage().read() as
+      | ({ githubModels?: GithubModelsCredentialBlob } & Record<string, unknown>)
+      | null
+    const t = data?.githubModels?.accessToken?.trim()
+    return t || undefined
+  } catch {
+    return undefined
+  }
+}
+
+/**
+ * If GitHub Models mode is on and no token is in the environment, copy the
+ * stored token into process.env so the OpenAI shim and validation see it.
+ */
+export function hydrateGithubModelsTokenFromSecureStorage(): void {
+  if (!isEnvTruthy(process.env.CLAUDE_CODE_USE_GITHUB)) {
+    return
+  }
+  if (process.env.GITHUB_TOKEN?.trim() || process.env.GH_TOKEN?.trim()) {
+    return
+  }
+  if (isBareMode()) {
+    return
+  }
+  const t = readGithubModelsToken()
+  if (t) {
+    process.env.GITHUB_TOKEN = t
+  }
+}
+
+export function saveGithubModelsToken(token: string): {
+  success: boolean
+  warning?: string
+} {
+  if (isBareMode()) {
+    return { success: false, warning: 'Bare mode: secure storage is disabled.' }
+  }
+  const trimmed = token.trim()
+  if (!trimmed) {
+    return { success: false, warning: 'Token is empty.' }
+  }
+  const secureStorage = getSecureStorage()
+  const prev = secureStorage.read() || {}
+  const merged = {
+    ...(prev as Record<string, unknown>),
+    [GITHUB_MODELS_STORAGE_KEY]: { accessToken: trimmed },
+  }
+  return secureStorage.update(merged as typeof prev)
+}
+
+export function clearGithubModelsToken(): { success: boolean; warning?: string } {
+  if (isBareMode()) {
+    return { success: true }
+  }
+  const secureStorage = getSecureStorage()
+  const prev = secureStorage.read() || {}
+  const next = { ...(prev as Record<string, unknown>) }
+  delete next[GITHUB_MODELS_STORAGE_KEY]
+  return secureStorage.update(next as typeof prev)
+}