fix: Export TanStackQueryProvider as default for Query Client addon

[abbas-roholamin]

Previously, in issue #372, the Query Client addon file only exported getContext(), which returned a QueryClient instance.

This change adds and exports TanStackQueryProvider as the default export, wrapping the app with QueryClientProvider using the queryClient from getContext(). It can also close the PR #373

This ensures:

• Consumers can directly use the provider as the default export
• The Query addon works correctly without requiring manual provider setup
• No changes to query configuration logic — only the provider export structure was updated

[tannerlinsley]

Superseded by #382, which includes a full fix for query provider scaffolding in both query-only and tRPC+query generated apps (with validated smoke builds).