feat(inbox): un utilisateur a DEUX inboxes, comme en amont

Tranché par la cascade plutôt qu'en attendant une réponse : le niveau 3 (ORM) ne
dit rien des inbox, le niveau 2 non plus — `@ng-org/web` n'expose aucune méthode
contenant « inbox » et la session n'en publie aucune. C'est donc le modèle du
moteur qui décide, et il dit DEUX : un site porte une inbox sur son repo de store
public et une autre sur son protégé (`engine/verifier/src/site.rs:127-152`), les
seuls `AddInboxCap` du moteur, `new_store_default` n'en posant une que
`if !private`. Elles sont adressées séparément jusque dans les enregistrements de
contact, qui choisissent leur prédicat selon le profil visé — `ng:site_inbox` pour
un profil public, `ng:protected_inbox` sinon
(`engine/verifier/src/inbox_processor.rs:787,823-824`).

`userInbox(id)` en exposait une : une cardinalité que cette bibliothèque avait
inventée, et que le nom `walletInbox` avait contribué à masquer. Elle prend
désormais le scope, et le store PRIVÉ n'en a pas — d'où `InboxScope` plutôt que
`Scope` : demander l'inbox privée n'est pas une recherche qui ne rend rien, c'est
une question sans référent dans le modèle, et le type l'interdit.

`myInboxes` énumère les deux, `isOwnInbox` reconnaît les deux. Le shim garde un
triple par (user, scope).

160 tests unitaires, typecheck src/test/e2e vert, e2e 40/40 contre le broker.

docs/api-contract.md

@@ -1,5 +1,7 @@
 # API contract — what `@ng-eventually/client` exposes today, and what the future SDK should expose per subject
 
+> **Updated 2026-08-03, after the source layout was reorganised by migration fate** (`docs/source-layout-by-fate.md`). Paths, and three names, changed under this document: `readModel` became the directly-exported `readUnion`; `accounts` / `AccountRecord` / `AccountStorage` became `virtualUsers` / `VirtualUserRecord` / `VirtualUserStorage` (module `shared-wallet/virtual-users.ts`); `store-registry-api.ts` became `surface/placement.ts`. Two modules were created and are covered here: `emulated-verifier/branch-registers.ts` (the four durable registers, split out of the shim) and `shared-wallet/bootstrap.ts` (the injection store, split out of the `/polyfill` entry). The subject-by-subject rulings below are unaffected — what moved is where the code lives, not what it promises.
+
 **Scope: the APP-FACING contract only.** Everything reachable from the two published entry points, and nothing else. The library's internal modules — the shim machinery, the read paths, the boundary guards — are held to the same standard (as close as possible to what NextGraph does or plans) but have their own document, `docs/internal-contract.md`: a consumer never reads that one, a maintainer does. This split was made on 2026-08-03, together with the export change described in § 15.
 
 **Scope.** The real exported surface of `@ng-eventually/client` (verified against the `export` statements in `packages/client/src/index.ts` and `packages/client/src/polyfill.ts` — `package.json` maps exactly two entry points, `.` and `./polyfill`), and, for each subject, the target signature the future NextGraph JS SDK is expected to expose. Written 2026-08-03, verified against the `nextgraph-rs` clone (HEAD `213338f6`, 2026-05-16) and the installed `@ng-org/web@0.1.2-alpha.13` type declarations (`node_modules/.bun/@ng-org+web@0.1.2-alpha.13/node_modules/@ng-org/web/dist/index.d.ts`, hereafter `index.d.ts`).
@@ -285,7 +287,7 @@ declare function sparql_query(session_id: any, sparql: string, base: any, nuri:
 
 `depositInto` has **NO COUNTERPART as a SPARQL write**: upstream a deposit is a sealed message, not an update into the recipient's graph (§ 9). It exists only because the emulated inbox is an RDF document.
 
-**Store targeting — a nuance this repo's docs understate.** `docs/nextgraph-current-state.md` and `docs/migration-guide.md` say a public/arbitrary `StoreRepo` "is not JS-constructible". Verified in the clone, the picture is finer:
+**Store targeting — finer than "not JS-constructible".** *(The other docs were corrected on 2026-08-03 to match this entry; they used to state the blanket form.)* Verified in the clone:
 
 - The **web** wasm variant (`sdk/js/lib-wasm/src/lib.rs:1575`, `#[cfg(not(wasmpack_target = "nodejs"))]`) deserializes its 5th argument as `Option<StoreRepo>` via serde — so a value CAN be passed, but no JS helper exists to build the serde form, which keeps it out of practical reach. The published `.d.ts` documents this 5-arg form.
 - The **nodejs** variant (`lib.rs:1618`, 6 args) takes `store_type: Option<String>` + `store_repo: Option<String>` and builds the store via `StoreRepo::from_type_and_repo(store_type, repo_id_str)` with `store_type ∈ "public" | "protected" | "private" | "group"` (`sdk/rust/src/local_broker.rs:2969-2987`, `engine/repo/src/types.rs:819-828`).
@@ -594,7 +596,7 @@ Exported, but not SDK surface. Coding against these builds knowledge that migrat
 
 ### Places the current surface teaches something to unlearn
 
-- ~~**The SDK entry is not as pure as its header claims.**~~ **FIXED 2026-08-03.** The header claimed the entry "exposes ONLY what `@ng-org/web` / `@ng-org/orm` expose" while also shipping `accounts` and the whole `store-registry` module. Both are gone from it, and the header now states what the entry actually promises: *every symbol here has a target-SDK counterpart, verified or assumed, listed in this document*. It still exports `docs`, `readModel`, `watchShape`, `subscribeDoc(s)`, the SPARQL helpers and the NURI guards — justified inventions, documented per subject above — so the promise is no longer "@ng-org surface only", which was never true, but "nothing here is machinery".
+- ~~**The SDK entry is not as pure as its header claims.**~~ **FIXED 2026-08-03.** The header claimed the entry "exposes ONLY what `@ng-org/web` / `@ng-org/orm` expose" while also shipping `virtualUsers` and the whole `store-registry` module. Both are gone from it, and the header now states what the entry actually promises: *every symbol here has a target-SDK counterpart, verified or assumed, listed in this document*. It still exports `docs`, `readUnion`, `watchShape`, `subscribeDoc(s)`, the SPARQL helpers and the NURI guards — justified inventions, documented per subject above — so the promise is no longer "@ng-org surface only", which was never true, but "nothing here is machinery".
 - **`shareCap` is importable from both entries** (`inbox.shareCap` on the SDK entry via `export * as inbox`, and a named re-export on `/polyfill`). The polyfill re-export exists "so the cap vocabulary stays on the polyfill side" — but the namespace export undoes that. Harmless functionally; blurs the same boundary.
 - **`inbox.read`/`materialize` as a mailbox** — enumerating raw deposits is emulation detail (§ 9); the durable contract is deposit-and-it-gets-applied. An app building UI on the deposit list should expect that surface to change shape entirely.
 - **`watchShape`'s "planned `useShape` upgrade"** — stated in the module header with no provenance in this repo or the clone (§ 5). The load-state *distinction* is safe; the claim that NextGraph plans this exact hook shape is an assumption and must not be cited as an announced API.
@@ -605,7 +607,7 @@ Exported, but not SDK surface. Coding against these builds knowledge that migrat
 
 ## Appendix — full export inventory (for diffing)
 
-`@ng-eventually/client` (from `index.ts`): types `Nuri`, `ReadCap`, `Scope`, `PrincipalId`, `NgLike`, `UseShapeLike`, `ShapeQuery`, `ShapeObservable`, `DocChange`, `DocChangeType`, `Unsubscribe`, `UnionSubject`, `VirtualUserRecord`, `RegistrySession`, `VirtualUserStorage`, `Deposit`, `PostOptions` (via namespaces), re-exported `ShapeType`, `BaseType`, `Schema`, `DeepSignalSet`, `NG`; values `ng`, `useShape`, `watchShape`, `init`, `initNg`, `subscribeDoc`, `subscribeDocs`, `docChangeType`, `escapeLiteral`, `escapeIri`, `assertNuri`, `isNuri`, `hasReadCap`; namespaces `inbox` (`post`, `postToDocument`, `shareCap`, `read`, `materialize`, `readSynced`, `processInbox`, `watch`), `docs` (`docCreate`, `sparqlUpdate`, `sparqlQuery`, `depositInto`), `readModel` (`readUnion`), `storeRegistry` (`reservedAccount`, `resetRegistryCache`, `resolveAccount`, `ensureAccount`, `resolveWriteGraph`, `resolveScopeGraph`, `userInbox`, `isOwnInbox`, `createEntityDoc`, `userStoreDoc`, `openDocumentInbox`, `documentInboxAddress`, `myInboxes`, `addLink`, `readLinks`, `listMyEntityDocs`), `accounts` (`ACCOUNT_STORAGE_KEY`, `IdentityStore`, `browserIdentityStore`).
+`@ng-eventually/client` (from `index.ts`): types `Nuri`, `ReadCap`, `Scope`, `PrincipalId`, `NgLike`, `UseShapeLike`, `ShapeQuery`, `ShapeObservable`, `DocChange`, `DocChangeType`, `Unsubscribe`, `UnionSubject`, `VirtualUserRecord`, `RegistrySession`, `VirtualUserStorage`, `Deposit`, `PostOptions` (via namespaces), re-exported `ShapeType`, `BaseType`, `Schema`, `DeepSignalSet`, `NG`; values `ng`, `useShape`, `watchShape`, `init`, `initNg`, `subscribeDoc`, `subscribeDocs`, `docChangeType`, `escapeLiteral`, `escapeIri`, `assertNuri`, `isNuri`, `hasReadCap`; namespaces `inbox` (`post`, `postToDocument`, `shareCap`, `read`, `materialize`, `readSynced`, `processInbox`, `watch`), `docs` (`docCreate`, `sparqlUpdate`, `sparqlQuery`, `depositInto`), `readUnion` (`readUnion`), `storeRegistry` (`reservedAccount`, `resetRegistryCache`, `resolveAccount`, `ensureAccount`, `resolveWriteGraph`, `resolveScopeGraph`, `userInbox`, `isOwnInbox`, `createEntityDoc`, `userStoreDoc`, `openDocumentInbox`, `documentInboxAddress`, `myInboxes`, `addLink`, `readLinks`, `listMyEntityDocs`), `virtualUsers` (`ACCOUNT_STORAGE_KEY`, `IdentityStore`, `browserIdentityStore`).
 
 `@ng-eventually/client/polyfill` (from `polyfill.ts`): types `StoreRegistryDeps`, `EventuallyConfig`; values `configure`, `getConfig`, `resetConfig`, `configureStoreRegistry`, `getStoreRegistryDeps`, `resetStoreRegistry`, `setCurrentUser`, `getCurrentUser`, `getCaps`, `capFor`, `resetCaps`, `CapRegistry`, `shareCap`, `connectedUser`.