Get Sec 13F Debug

2026-08-26 (debugging Berkshire's 0-holdings result -- confirmed reproducible: 3 manual refreshes, Berkshire fails all 3 times while Pershing Square/Scion succeed every time, so this is specific to Berkshire's filing, not a flaky network issue). Runs the exact same 3-step pipeline services.sec_ownership_service.refresh_filer() uses (submissions.json -> filing index.json -> info table XML), but returns each intermediate result instead of just persisting/failing silently, so we can see exactly which step breaks for this CIK.