Prod capture (traffic_prod_misc_clicking.ndjson) shows all three
MyPageBgSetting fields arrive as decimal strings, not ints. Update the
DTO from int/int/List<int> to string/string/List<string> with "0"/empty
defaults, and add a literal wire-shape round-trip test pinning the
exact JSON against the capture.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>