CngxTocRouterSync

Deep-links a CngxToc into the URL fragment. Opt-in via [cngxTocRouterSync] on the same host as <cngx-toc>: activating a link writes #<section-id> (replacing the history entry, so a scroll-driven rail never floods the back stack), and a deep link like /guide#pricing scrolls to that section once on load.

Reaches the rail through the CNGX_TOC contract token, never the concrete CngxToc class. The activation subscription is torn down with the directive via takeUntilDestroyed - an OutputRef subscription would otherwise outlive route changes. Without @angular/router the directive dev-warns once and no-ops.

https://cngxjs.github.io/cngx/examples/#/ui/toc/router/fragment-deep-link