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/managedEnvConstants.ts

@@ -18,6 +18,7 @@ const PROVIDER_MANAGED_ENV_VARS = new Set([
   'CLAUDE_CODE_USE_BEDROCK',
   'CLAUDE_CODE_USE_VERTEX',
   'CLAUDE_CODE_USE_FOUNDRY',
+  'CLAUDE_CODE_USE_GITHUB',
   // Endpoint config (base URLs, project/resource identifiers)
   'ANTHROPIC_BASE_URL',
   'ANTHROPIC_BEDROCK_BASE_URL',
@@ -147,6 +148,7 @@ export const SAFE_ENV_VARS = new Set([
   'CLAUDE_CODE_SUBAGENT_MODEL',
   'CLAUDE_CODE_USE_BEDROCK',
   'CLAUDE_CODE_USE_FOUNDRY',
+  'CLAUDE_CODE_USE_GITHUB',
   'CLAUDE_CODE_USE_VERTEX',
   'DISABLE_AUTOUPDATER',
   'DISABLE_BUG_COMMAND',