docs: dire partout que la lecture par lot n'existe plus

Le contrat publie et l'api-contract etaient traites avec le retrait lui-meme ;
restaient les documents qui decrivaient readUnion comme la primitive de
lecture du paquet, ou qui nommaient le module disparu.

Ce que les lecteurs apprennent maintenant : lire un document, c'est
docs.sparqlQuery ancre dessus, et lire plusieurs documents, c'est cet appel
une fois par document -- avec la decision sur une lecture qui echoue ecrite
au point d'appel. Deux consequences sont dites plutot que decouvertes : une
lecture refusee leve au lieu de rendre une liste vide, et les sujets sous le
prefixe reserve urn:ng-eventually: reviennent dans le resultat, a l'appelant
de les ignorer -- sans aucun gain de droits, les deux registres qu'un
document ordinaire porte etant l'adresse de sa boite et, pour un document
public, la cle que son magasin sert deja a qui la demande.

Les briefs dates ne sont pas touches : ils decrivent un etat de juillet, et
le reecrire falsifierait ce qui avait ete decide alors.

packages/polyfill/README.md

@@ -2,7 +2,7 @@
 
 One entry point. Most of what it publishes has the same signature as the future SDK —
 `ng`, `useShape`, `useShapeQuery`, `getObjects`, `insertObject`, `docs`, `inbox`,
-`storeRegistry`, `readUnion` (+ types) -
+`storeRegistry` (+ types) -
 and is a drop-in for `@ng-org/web` / `@ng-org/orm`: as NextGraph matures it resolves to
 the real SDK (build alias removed) with no code change.
 
@@ -28,7 +28,7 @@ Per-symbol, with the target signature and an epistemic label on every claim:
 ```ts
 import {
   // SDK-shaped — the real SDK replaces these in place.
-  ensureIdentity, storeRegistry, inbox, readUnion, docs,
+  ensureIdentity, storeRegistry, inbox, docs,
   // Polyfill-era — one call, and it is the whole of what goes away.
   configure,
 } from "@ng-eventually/polyfill";
@@ -91,7 +91,7 @@ which the e2e suite drives.
 ## How a document is reached — the three acts, and no others
 
 ```ts
-import { storeRegistry, inbox, readUnion } from "@ng-eventually/polyfill";
+import { storeRegistry, inbox, docs } from "@ng-eventually/polyfill";
 
 // 1. CREATE — you hold its cap, with nothing to declare. No identity parameter: a
 //    session belongs to one user, exactly as the target's own `doc_create` assumes.
@@ -109,7 +109,11 @@ await inbox.share(doc, "bob");
 //    it and opens nothing.
 const publicDoc = await storeRegistry.createEntityDoc("public");
 // …put `publicDoc` in a QR code, a message, another document. Nothing else to do.
-await readUnion([publicDoc]);   // a stranger holding only this reads it
+// A stranger holding only that reference reads it with ONE anchored query — the anchor
+// scopes the read to that document's own graph, and the key is fetched from the public
+// store on the way in. `readUnion([publicDoc])` did this until `1.0.0-dev.8`; it was
+// this call in a loop, so the loop is yours now and the call is unchanged.
+await docs.sparqlQuery(sessionId, "SELECT ?s ?p ?o WHERE { ?s ?p ?o }", undefined, publicDoc);
 ```
 
 **The invariant behind all three: you never derive a cap from a bare reference.** You
@@ -139,5 +143,6 @@ runtime checks stay regardless — a JavaScript caller never meets the compiler.
 
 ```ts
 const saved = localStorage.getItem("doc");        // string | null
-if (saved) await readUnion([saved]);              // ✓ validated at the door
+// ✓ validated at the door — `anchor` is a `NuriLike`, so nothing to narrow here
+if (saved) await docs.sparqlQuery(sessionId, "SELECT ?s ?p ?o WHERE { ?s ?p ?o }", undefined, saved);
 ```