fix(cloudflare/containers): bind a container's DO namespace and script metadata under one sid

[spinx]

A Cloudflare.Container bound on an async Worker's env uploaded as a json binding holding the serialized declaration ({"_id":"Effect","op":"alchemy/EffectClass"}) instead of a durable_object_namespace, whenever the env key and the Container's logical id matched:

env: { Sandbox: Cloudflare.Container("Sandbox", { className: "Sandbox", context, dockerfile }) }

At runtime env.Sandbox is then a plain object, and @cloudflare/sandbox's getSandbox(ns, id) dies with t.idFromName is not a function.

bindContainerClass contributed the Worker's two halves in separate bind calls, and binding rows are collapsed by sid — last write wins (Diff.ts), so the containers row silently dropped the namespace row:

-yield* resource.bind`${bindingName}`({ bindings: [durableObjectNamespace] });   // sid = "Sandbox"
-yield* resource.bind`${application.LogicalId}`({ containers: [{ className }] }); // sid = "Sandbox"
+yield* resource.bind`${bindingName}`({
+  bindings: [durableObjectNamespace],
+  containers: [{ className }],
+});

Both rows describe the same env entry, so they belong under one sid. With them split, the upload carried no DO class at all (currentDoClassNameByLogicalId: {}), and appendAlchemyAndEnvBindings — which JSON-ifies any env value not already bound by name — emitted the declaration as json.

The existing async fixture escaped this by naming the Container AsyncEchoContainer while binding it as env.ECHO; it now uses Container("ECHO") so the live suite covers the colliding shape. A new offline test (AsyncContainerBinding.test.ts) pins the sid-collapsed rows for both namings.

Workaround on released versions: give the Container a logical id that differs from the env key.