Add four providers: CTYun OOS (ctyun, unified + resource-pool + Hong Kong endpoints), CUCloud OSS (cucloud, industry-cloud regions), China Mobile EOS (eos, 30 public regions), QingCloud QStor (qingstor, S3-compatible qsstor.com); wired into --provider, find probes and URL auto-recognition (default find probes 71 -> 130, --global 167 -> 226).
Implement URL recognition for Wasabi, DigitalOcean Spaces, Yandex, Exoscale and Arvan (documented before but never matched in code).
Document unsupported vendors with reasons: UPYUN USS (proprietary REST protocol, not S3-compatible); Qiniu Kodo stays removed (anonymous probes always 400; bucket domains are bound CDN domains).
Replace a leftover private test bucket name in scan_test.go with a neutral placeholder.