Export ProviderConfig from Node.js and Python SDKs (#1048)

ProviderConfig was defined in both SDKs but not re-exported from
their public API entry points. Consumers had to duplicate the type
locally to use it for Responses API configuration (wireApi: 'responses').

- Node.js: add ProviderConfig to the type re-exports in src/index.ts
- Python: import ProviderConfig in copilot/__init__.py and add to __all__

Fixes github/copilot-sdk-partners#7

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: stephentoub

nodejs/src/index.ts

@@ -47,6 +47,7 @@ export type {
     PermissionHandler,
     PermissionRequest,
     PermissionRequestResult,
+    ProviderConfig,
     ResumeSessionConfig,
     SectionOverride,
     SectionOverrideAction,

python/copilot/__init__.py

@@ -23,6 +23,7 @@
     ElicitationParams,
     ElicitationResult,
     InputOptions,
+    ProviderConfig,
     SessionCapabilities,
     SessionFsConfig,
     SessionFsHandler,
@@ -49,6 +50,7 @@
     "ModelLimitsOverride",
     "ModelSupportsOverride",
     "ModelVisionLimitsOverride",
+    "ProviderConfig",
     "SessionCapabilities",
     "SessionFsConfig",
     "SessionFsHandler",