feat(fp): WP-06 — kill $any() in templates (18x)

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.

docs/backlog/README.md

@@ -45,7 +45,7 @@ for its existing violations, so every WP ends green.
 | [WP-03](WP-03-contracts-purity.md)      | Boundaries I: contracts purity + ApiClient confinement       | 0 · gates                   | done   |
 | [WP-04](WP-04-ui-not-infrastructure.md) | Boundaries II: `ui ↛ infrastructure` + showcase sanction     | 0 · gates                   | done   |
 | [WP-05](WP-05-parse-boundaries.md)      | Parse-don't-validate closure + MDX                           | 1 · FP/DDD                  | done   |
-| [WP-06](WP-06-typed-async.md)           | Generic async template contexts — kill `$any()`              | 1 · FP/DDD                  | todo   |
+| [WP-06](WP-06-typed-async.md)           | Generic async template contexts — kill `$any()`              | 1 · FP/DDD                  | done   |
 | [WP-07](WP-07-brief-idioms.md)          | Brief on the shared idioms + RemoteData MDX                  | 1 · FP/DDD                  | todo   |
 | [WP-08](WP-08-store-idiom.md)           | One store idiom + machine naming + TEA MDX                   | 1 · FP/DDD                  | todo   |
 | [WP-09](WP-09-pure-logic.md)            | Pure-logic closure: dates + missing command specs            | 1 · FP/DDD                  | todo   |