feat(cloudflare): run DO-attached containers in alchemy dev

[Butch78]

Run Durable-Object-attached containers under alchemy dev, using workerd's native container support against the local Docker daemon (what wrangler dev / miniflare do).

A worker binds a container class to a DO namespace with an image name; locally that image is started per DO instance and exposed as ctx.container:

yield* worker.bind`my-container`({
  containers: [{ className: "MyDo", imageName: "my-image:dev" }],
});

• containers binding data gains an optional imageName; entries without one are remote-only attachments and are ignored locally (ctx.container stays absent)
• LocalWorkerProvider maps className -> imageName from binding data, attaches container: { imageName } to the matching workerd DO namespace, and configures a localDocker container engine (socket unix:///var/run/docker.sock)
• The egress-interceptor sidecar image defaults to the same pinned cloudflare/proxy-everything miniflare uses; ALCHEMY_CONTAINER_EGRESS_IMAGE overrides it (e.g. to work around Containers local dev sidecar can intercept Docker bridge traffic and break readiness cloudflare/workerd#6792 on hosts where TPROXY intercepts bridge-local traffic and hangs the sidecar readiness probe)

Draft because it activates only once @distilled.cloud/cloudflare-runtime threads the container config through to workerd: alchemy-run/cloudflare-tools#46, then a catalog bump here. The new fields typecheck against 0.10.12 and are dropped by its config assembly, so behavior is unchanged until that lands.

Validated end-to-end on the cloudflare-tools#46 runtime: a Rust DataFusion container attached to a DO class under alchemy dev cold-starts on first request, serves proxied traffic, and is destroyed by the DO's idle alarm.

[Butch78]

Added unit tests in 472532b (test/Cloudflare/Workers/LocalWorkerProvider.test.ts). Pulled the inline className -> imageName loop out into an exported, documented collectContainerImages helper and exported toRuntimeDurableObjectNamespaces, so both are covered directly: remote-only attachments (no imageName) are skipped, className collisions take the last write, and the container field is attached only to namespaces that have a mapped image. Still draft pending cloudflare-tools#46 + the catalog bump.