v2.3.1

Changed

• frontend skill: the invite-accept flow diagram (references/auth_ui.md) reflects the CLI 2.3.1 scaffold. A new user accepting an invitation with email confirmation on now routes through the shared /check-inbox?type=signup step (paste the 8-digit OTP or click the link) and lands back on /accept-invite to auto-join — instead of the old bare "click the link" card. The diagram also drops a stale /sign-in bounce (the page is self-contained with an inline create-account / sign-in form) and notes the ["tenants"] cache refresh before landing on /dashboard. Keeps the plugin in lockstep with the CLI's 2.3.1 scaffold (invite-accept OTP step, invite-accept sign-out-race fix, and the route-guard query-cache fix).