CVE-2026-54497: ViewComponent: Reused Component Instances Retain Stale Render Context

ViewComponent::Base instances retain multiple render-scoped objects across calls to render_in. If the same component, collection, or spacer component instance is reused across requests, users, tenants, or threads, later renders can use stale helpers, controller, request, view_flow, format/variant details, and slot child context from an earlier render.

This can cause authorization-aware components to render privileged UI for a lower-privileged user, generate links using a stale Host header, leak slot/helper state, and mix request context under concurrent rendering.