Make AsyncLoadedDirective generic with a static ngTemplateContextGuard for
AsyncComponent's own internal typing. That can't propagate to consumer
`<ng-template appAsyncLoaded let-p>` sites though -- Angular only infers a
structural directive's type parameter from an input bound on that same
node, not from a sibling input on the parent component -- so the ~9
root-cause consumers (dashboard, registration-detail, aanvraag-detail,
registratie-wizard) instead unwrap the RemoteData Success value via a
typed computed() and narrow it locally with `@if (x(); as p)`. The
remaining union-narrowing casts (registration-summary, showcase concepts
page) are replaced with a stable @let binding and a direct resource read,
respectively. Documented as a deviation in WP-06's backlog file.
Turns the prior roadmap sketch into ordered, gated work packages (enforcement
gates, FP/DDD consistency, CIBG fidelity, Storybook curriculum, a11y) from the
2026-07-02 showcase-hardening audit.
