feat(p9): scope-ownership assert + fence routing approve/deny/listDecisions

Task T3.1: ActorResolver gains findScope (no-create) + assertOwns(principal,
resourceScopeId) → ForbiddenException on mismatch (KG-02). RouteService.approve/
deny now assertOwns on the decision's binding scope before mutating; listDecisions
is scoped to the caller. Fixes the critical cross-tenant mutation (tenant A could
approve tenant B's route). Also adds IiosScope.cellId + IiosOutboundCommand.scopeId
columns (migration tenant-isolation) + cell assignment on scope create. Test:
another tenant approving → Forbidden, decision unchanged, no scope created, empty list.

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

packages/iios-service/src/routing/route.spec.ts

@@ -123,6 +123,25 @@ describe('RouteService approve/deny → execute (P6)', () => {
     expect(await prisma.iiosOutboundCommand.count()).toBe(1); // dispatched to sandbox
   });
 
+  it('tenant fence: another tenant cannot approve this tenant’s decision (KG-02)', async () => {
+    const { interactionId, scopeId } = await makeInteraction('party at 9 PM');
+    await makeBinding(scopeId, 'seniors', 'SENIORS');
+    const service = svc();
+    await service.simulate(interactionId, ORIGIN);
+    const b = await prisma.iiosRouteBinding.findFirstOrThrow({ where: { destinationRef: 'seniors' } });
+    const decision = await prisma.iiosRouteDecision.findUniqueOrThrow({
+      where: { interactionId_routeBindingId: { interactionId, routeBindingId: b.id } },
+    });
+
+    const tenantB: MessagePrincipal = { userId: 'intruder', orgId: 'org_other', appId: 'portal-demo', displayName: 'B' };
+    await expect(service.approve(decision.id, tenantB)).rejects.toThrow(/tenant scope/);
+    const after = await prisma.iiosRouteDecision.findUniqueOrThrow({ where: { id: decision.id } });
+    expect(after.decisionState).toBe('REVIEW'); // unchanged
+    expect(await prisma.iiosScope.findFirst({ where: { orgId: 'org_other' } })).toBeNull(); // no scope created for B
+    // B's decision list is empty (scoped to caller)
+    expect(await service.listDecisions(tenantB)).toHaveLength(0);
+  });
+
   it('denying a decision never executes', async () => {
     const { interactionId, scopeId } = await makeInteraction('party at 9 PM');
     await makeBinding(scopeId, 'children', 'CHILD');