feat(auth): staging wallet partagé — import assisté par fichier + e2e multi-navigateur

Stopgap staging multi-user sur wallet partagé (cf. brief_2026-06-15_shared-wallet-shim).

Distribution / import du wallet :
- AccessGateScreen : barrière d'accès ON PAR DÉFAUT (désactivable via
  globalThis.__FESTIPOD_ACCESS_GATE_DISABLED__ pour tests/dev). Fournit le FICHIER
  .ngw + le mot de passe + un guide en 3 étapes (import assisté sur nextgraph.eu —
  le broker hébergé n'autorise pas l'import inline pendant l'auth web-app).
- sharedWallet.ts + build.ts : fichier copié en /shared-wallet.ngw, mot de passe gravé.
- Ancien LoginScreen (/login) retiré ; atterrissage post-login -> /home.
- NextGraphContext : dé-piégeage de l'état "connecting" au retour (pageshow/bfcache).

Couche multistore stopgap : storeRegistry, isolation, AccountContext, FestipodDataContext.

Tests e2e multi-navigateur :
- browserPool + world.openBrowser : contextes frais isolés, 2 axes orthogonaux
  (nb de navigateurs × modèle de wallet own/shared).
- @humain : parcours humain complet (télécharge -> importe le fichier sur
  nextgraph.eu -> Entrer -> pseudo -> accueil).
- Bypass de la barrière pour @e2e via context.addInitScript.
- Convention @wip exclue via cucumber.json.

Docs (concepts) : nextgraph-platform (knowledge_broker-import-constraint,
decision_2026-06-17_assisted-wallet-import), bdd-testing (knowledge_multibrowser-harness).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/shared/test-harness/harness-ng.tsx

@@ -12,6 +12,7 @@ import { createRoot } from 'react-dom/client';
 import { NextGraphProvider, useNextGraph } from '../context/NextGraphContext';
 import { FestipodDataProvider, useFestipodData } from '../context/FestipodDataContext';
 import { useShape } from '@ng-org/orm/react';
+import { ng } from '@ng-org/web';
 import type { DeepSignalSet } from '@ng-org/alien-deepsignals';
 import {
   FpEventShapeType,
@@ -67,6 +68,11 @@ function ConnectedHarness() {
   const participations = useShape(FpParticipationShapeType, privateNuri) as DeepSignalSet<FpParticipation>;
 
   const [bridgeReady, setBridgeReady] = useState(false);
+  // Stopgap multi-store validation: a doc created on demand via doc_create,
+  // mounted into a real useShape({graphs}) by <SmokeProbe>.
+  const [smokeDoc, setSmokeDoc] = useState<string | null>(null);
+  // Per-entity fan-out validation: several entity docs read together.
+  const [fanoutGraphs, setFanoutGraphs] = useState<string[]>([]);
 
   useEffect(() => {
     // Small delay for useShape to populate
@@ -146,6 +152,54 @@ function ConnectedHarness() {
         loadTestData() {
           return bootstrapWallet(events as any, users as any, participations as any);
         },
+
+        // --- Stopgap multi-store validation (see brief_2026-06-15_shared-wallet-shim) ---
+
+        /**
+         * Create a fresh graph document via doc_create and mount it into a real
+         * useShape({graphs}) subscription (<SmokeProbe>). Returns the NURI.
+         * Validates: doc_create returns a usable graph NURI.
+         */
+        async createSmokeDoc() {
+          const nuri = await ng.doc_create(session.session_id, 'Graph', 'data:graph', 'store', undefined);
+          setSmokeDoc(nuri);
+          return nuri;
+        },
+
+        /**
+         * Round-trip the sharedWalletShim through the wallet: create an account
+         * (3 docs + SPARQL INSERT), drop the cache, reload from the wallet via
+         * SPARQL SELECT. Validates: doc_create ×3 + shim sparql_update/query.
+         */
+        async validateShim(username: string) {
+          const reg = await import('../utils/storeRegistry');
+          reg.resetRegistryCache();
+          const created = await reg.ensureAccount(username);
+          reg.resetRegistryCache();
+          const reloaded = (await reg.allAccounts()).find(
+            a => a.username === username,
+          ) ?? null;
+          return { created, reloaded };
+        },
+
+        /**
+         * Per-entity granularity + fan-out: 2 accounts, one event document each
+         * (via createEntityDoc → indexed), then mount a multi-graph useShape over
+         * both (<FanoutProbe>). Returns the two doc NURIs and the index listing.
+         * Validates: 1-doc-per-entity, index append/read, fan-out across N docs.
+         */
+        async setupFanout() {
+          const reg = await import('../utils/storeRegistry');
+          reg.resetRegistryCache();
+          await reg.ensureAccount('@fan-a');
+          await reg.ensureAccount('@fan-b');
+          const docA = await reg.createEntityDoc('@fan-a', 'public');
+          const docB = await reg.createEntityDoc('@fan-b', 'public');
+          reg.resetRegistryCache();
+          const listed = await reg.listEntityDocs('public');
+          setFanoutGraphs([docA, docB]);
+          return { docA, docB, listed };
+        },
       };
 
       console.log('[HarnessNG] Ready — events:', events.size, 'users:', users.size,
@@ -157,7 +211,70 @@ function ConnectedHarness() {
     return () => clearTimeout(timer);
   }, [events, users, participations, ngCtx, appData]);
 
-  return <div id="harness-status">{bridgeReady ? 'READY' : 'LOADING_SHAPES'}</div>;
+  return (
+    <>
+      <div id="harness-status">{bridgeReady ? 'READY' : 'LOADING_SHAPES'}</div>
+      {smokeDoc && <SmokeProbe docNuri={smokeDoc} />}
+      {fanoutGraphs.length > 0 && <FanoutProbe graphs={fanoutGraphs} />}
+    </>
+  );
+}
+
+// ============================================================================
+// FanoutProbe — real useShape({graphs}) over SEVERAL entity documents.
+// Exposes window.__fanout for the per-entity fan-out @data scenario.
+// ============================================================================
+
+function FanoutProbe({ graphs }: { graphs: string[] }) {
+  const set = useShape(FpEventShapeType, { graphs } as any) as DeepSignalSet<FpEvent>;
+  useEffect(() => {
+    (window as any).__fanout = {
+      ready: true,
+      graphs,
+      addEventTo(docNuri: string, title: string) {
+        set.add({
+          '@graph': docNuri,
+          '@type': 'http://festipod.org/Event',
+          '@id': '',
+          title,
+          participantCount: 1,
+        } as FpEvent);
+      },
+      count() { return set.size; },
+      titles() { return [...set].map(e => e.title); },
+    };
+  }, [set, graphs]);
+  return null;
+}
+
+// ============================================================================
+// SmokeProbe — real useShape({graphs}) on a doc_create'd document.
+// Exposes window.__smoke for the multi-store @data validation scenario.
+// ============================================================================
+
+function SmokeProbe({ docNuri }: { docNuri: string }) {
+  const set = useShape(FpParticipationShapeType, { graphs: [docNuri] } as any) as DeepSignalSet<FpParticipation>;
+  useEffect(() => {
+    (window as any).__smoke = {
+      ready: true,
+      docNuri,
+      add() {
+        set.add({
+          '@graph': docNuri,
+          '@type': 'http://festipod.org/Participation',
+          '@id': '',
+          event: 'urn:smoke:event',
+          user: 'urn:smoke:user',
+          isConfirmed: true,
+        } as FpParticipation);
+      },
+      count() { return set.size; },
+      items() {
+        return [...set].map(p => ({ '@id': p['@id'], event: p.event, user: p.user }));
+      },
+    };
+  }, [set, docNuri]);
+  return null;
 }
 
 // ============================================================================