WithMaxResponseBody wrapped the body in io.LimitedReader, which returns EOF
at the cap, so Bytes/JSON/XML silently returned a truncated body with a nil
error despite the documented contract. Read one byte past the limit and
return the new ErrResponseTooLarge sentinel when exceeded; bodies exactly at
the limit still succeed.
Wraps response body with io.LimitedReader when configured, preventing
unbounded reads from io.ReadAll in Response.Bytes(). Protects against
upstream services returning unexpectedly large responses.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
