HomeProxy / Karing lightweight subscription stabilizer

Routes:
  /sub.json?token=YOUR_TOKEN    Output fixed sing-box outbounds JSON
  /health?token=YOUR_TOKEN      Show last build status and traffic info

Required secrets / variables:
  UPSTREAM_URL
  ACCESS_TOKEN

Required KV binding:
  CONFIG_KV

Optional variables:
  UPSTREAM_USER_AGENT=sing-box 1.13.0
  FALLBACK_REGION=US
  REGION_COUNT=5
  ALPN=h2
  STRIP_DOMAIN_RESOLVER=false