Expose request statistics on ApifyClient #1175

ApifyClient keeps its counters in a private _statistics attribute (_apify_client.py#L170) and hands it only to the default ImpitHttpClient (#L284). with_custom_http_client sets _http_client and leaves _statistics alone (#L257-L261), so with a custom client the root object's counters stay at zero while the HTTP client counts into its own ClientStatistics (_base.py#L152). ClientStatistics is not exported either (_statistics.py), so there is no supported way to read calls, requests, or rate-limit errors.

The JS client has a public client.stats (apify_client.ts#L120-L124) and points it at the custom HTTP client's stats when one is assigned (#L231-L235). Statistics is exported (statistics.ts).

Expected behavior

A public read-only statistics property on ApifyClient and ApifyClientAsync that returns the statistics of the HTTP client actually in use, custom or default, with ClientStatistics exported from apify_client.

✍️ Drafted by Claude Code