docs: corriger la justification fausse a cote de l'assertion d'etat de synchro

Le commentaire affirmait qu'aucune des deux valeurs ne permet de prendre une
lecture a zero ligne pour une absence definitive. `unknown` le permet, et
deliberement : `index-deposit.noRowsMeansAbsent` l'accepte, parce que la ou il
n'y a pas de semantique `State` il n'y a pas de barriere a avoir manquee. Les
deux valeurs ne sont pas interchangeables, et laquelle est juste depend de la
page - ce que l'assertion epingle dans les deux mondes est la meme chose : pas
`"synced"`.

packages/polyfill/test/cold-read-for-document.test.ts

@@ -116,14 +116,20 @@ describe("reading the messages left on my note, on a page that has just loaded",
     // ...because nothing on THIS page ever brought the NOTE into view. The address lives
     // on it.
     //
-    // `"timed-out"`, not `"unknown"`, since 2026-09-24: a registry reset now DOWNGRADES the
+    // `"timed-out"`, not `"unknown"`, since 2026-09-24: a reset DISOWNS the documents it takes
-    // documents it takes subscriptions away from instead of forgetting their state, so
+    // subscriptions away from rather than forgetting them, so `"unknown"` keeps its one
-    // `"unknown"` means only "no barrier was ever expected here" and can be read as
+    // meaning - "no barrier was ever expected here".
-    // authoritative. Note this particular value is a harness artefact and not what a real
+    //
-    // reload produces: `reloadPage` resets the registry inside one process, so the note is
+    // CORRECTED 2026-09-24, and the reason that used to stand here was FALSE. It said neither
-    // still in it from the first page, where a browser reload would start with an empty
+    // value lets a zero-row read be called a definitive absence: `unknown` does, and
-    // module and answer `"unknown"`. Either way it is the safe reading - neither value lets
+    // deliberately - `emulated-verifier/index-deposit.ts` `noRowsMeansAbsent` returns true for
-    // a zero-row read be called a definitive absence here.
+    // it, because where there are no `State` semantics there is no barrier to have missed. The
+    // two values are not interchangeable, and which one is correct depends on the page. This
+    // particular one is a harness artefact: `reloadPage` resets the registry inside ONE process,
+    // so the note is still known to it from the first page, and `"timed-out"` - "opened here,
+    // and no barrier to show for it" - is the exact truth. A browser reload starts with an empty
+    // module, where nothing was ever opened and `"unknown"` is the exact truth instead. What
+    // this line pins in both worlds is the same thing: not `"synced"`.
     expect(getSyncState(note)).toBe("timed-out");
   });