Subconverter Worker
Endpoints:
  /sub?target=clash&url=...&config=...
  /sub?target=singbox&url=...&config=...

Parameters:
  target  (required) - clash or singbox
  url     (required) - subscription URL
  config  (optional) - INI config URL
  scv     (optional) - skip cert verify (true/false)
  expand  (optional) - expand rulesets (true/false)