User report: `upload_private_file` was failing with "private file upload
host is invalid" on a fresh upload (boolFileExist=false). The OIDB call
succeeded but `uploadIp` (field 60) came back empty, and we treated
that single field as the only source of truth.
Cross-referenced LagrangeGo's `OidbSvcTrpcTcp0xE37_800.proto` + NapCat's
`Oidb.0XE37_800.ts`: the server has six parallel host slots on this
response (uploadIp / uploadDomain / uploadIpList[0] / uploadHttpsDomain
/ uploadDns / uploadLanip). LagrangeGo + Lagrange.Core only read field
60 and would hit the same dead-end — we walk the chain instead. Also
log the full slot set when we genuinely can't find a host so future
reports can name which field the server actually populated.
Adds two regression tests: one proves the fallback to `uploadDomain`
goes to highway successfully, one proves we still throw when every
slot is empty.
DrSmoothl
87ac6ffedb