Support for 'root' router direction, fixes #19982

Editor assessment

fix(react) says support is added for the root router direction, with the fix and issue references embedded inline in the header. The scope and type fit, and the subject is imperative and unterminated. The inline issue reference is understandable but mixes footer content into the subject, a minor hygiene lapse. No body explains the behavior. Clear and correctly classified, it is publishable with that style note.