chore: mesurer la forme du tableau au lieu de la supposer, et retirer les any

La branche tableau se decide sur `typeof cible.length === "number"`, ce qui est
une question posee a un proxy : mesure contre le vrai
`@ng-org/alien-deepsignals`, `deepSignal(new Set(...)).length` vaut `undefined`
et ses `Object.keys` sont vides, tandis que `deepSignal([...]).length` est un
nombre. La forme ensemble n-entre donc jamais dans cette branche, et c-est aussi
celle qui ne porte aucune cle nommant un objet.

Les trois `as any` des tests ajoutes et le `Iterable<any>` du harness sont
types.

packages/polyfill/src/emulated-verifier/read-filter.ts

@@ -213,6 +213,12 @@ export function makeReadFilteredView<S extends object>(set: S, caps: CapRegistry
    * `DeepSignal<ReadOnlyArray>` instead of a `DeepSignalSet`, and an array is addressed by
    * INDEX and counts itself with `length`. Decided from the target once, so the view never
    * grows a member the collection it wraps does not have.
+   *
+   * MEASURED against the real `@ng-org/alien-deepsignals` rather than assumed, because the
+   * collection is itself a proxy and what it answers for a key it does not carry is its
+   * business: `deepSignal(new Set(...)).length` is `undefined` and its `Object.keys` is
+   * empty, while `deepSignal([...]).length` is a number. So the set form never enters this
+   * branch, and the set form is also the one with no key naming an item to project.
    */
   const arrayLike = typeof (set as { length?: unknown }).length === "number";
   /** The index a key names, or `null` when it names no position in this collection. */