fix: align protected seat rotation semantics

fix: align provider auth seat semantics

fix: reduce rotation probe interference

fix: sync rotation account creation strategy

fix: complete autoteam-1 parity migration

fix: harden seat rotation and direct signup race

fix: 对齐注册轮转链路和 CloudMail 配置提示

feat: add ipv6 proxy pool and status surface

fix: harden Playwright and HTTP transport cleanup

fix(invite-hardening): round-2 实际修复落地 — invite/reconcile/standby/UI

fix: restore required setup fields

fix: stabilize main account status and reuse flow