Give the routes-test memory plane its capabilities field

The caller-resolver suite (CL-6286) builds a fake Memory that predates the
capabilities surface CL-6287 adds, so the two only stop typechecking once
both land on main.

Author: TheGreatAxios

src/routes/routes.test.ts

@@ -133,6 +133,7 @@ function stubMachinePlane(opts?: {
   const fed: { tenantId: string; principalId: string }[] = [];
   const catalog = opts?.timelineCatalog ?? [];
   const plane: Memory = {
+    capabilities: { embeddingsConfigured: true },
     search: async (p) => {
       searched.push({
         tenantId: p.tenantId,