`isKnownRoute` exempted both families behind TODOs waiting on route extraction
for those packages. That extraction had already landed when the TODOs were
written in #66254: cdk pages since #60853 and aria pages since the cross-repo
workflow. `defined-routes.json` carries 70 `api/cdk` and 39 `api/aria` routes
today, and all 45 such link targets in the guides resolve, so the build stays
green without the exemptions.
The gap was not theoretical. `guide/aria/select.md` and
`guide/aria/multiselect.md` linked `api/cdk/overlay/CdkConnectedOverlay`, which
has never been a route, and it shipped as a 404 for six months. Link validation
landed four months into that and said nothing, because of this exemption. It
took a user filing #68914 and an outside contributor fixing it in #68915.
Pointing an existing `api/cdk` link at a symbol that does not exist passes the
build today and fails it with this change.
The list of valid links is generated from navigation data configuration in the ADEV app.
Redirections are knowingly exclude so we stop referencing them.
Move the header id tracking into the renderer context rather than a global state. Since the RendererContext is
initialized for each execution of the marked parser, we can store the context of which header ids have been seen within
a single page there which allows us to run these parse interactions in parallel.
Improves the symbol linking logic to handle Angular component selectors (e.g., ngCombobox). It attempts to convert Angular selector patterns to their corresponding class names, improving navigation to Angular API documentation.
Kam