feat(wrangler): add container support to worker previews

[maxwellpeterson]

wrangler preview now supports containers via a new previews.containers configuration block.

Container configuration is non-inheritable: declare containers explicitly in the previews block to enable them for previews, mirroring how previews.durable_objects works today. Preview container application names are auto-generated by wrangler in the form {worker_name}_{preview_slug}_{class_name} and are not user-configurable — the config validator rejects entries that set a name field. Container applications bound to Durable Object classes implemented by another Worker (via script_name) are intentionally skipped, since the implementing Worker owns its own container application.

Container applications are created on wrangler preview and removed on wrangler preview delete. Cleanup matches applications by their auto-generated name prefix ({worker_name}_{preview_slug}_), so deletions are scoped to the specific preview being torn down. Failures on individual application deletes are logged as warnings but do not block the preview deletion itself.

This was originally part of #13712 and has been split out for easier review.

// wrangler.json
{
  "previews": {
    "durable_objects": {
      "bindings": [{ "name": "MY_CONTAINER", "class_name": "MyContainer" }]
    },
    "containers": [
      {
        "class_name": "MyContainer",
        "image": "registry.cloudflare.com/example:latest"
      }
    ]
  }
}

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s):
  • Documentation not necessary because:

[changeset-bot]

🦋 Changeset detected

Latest commit: aafe866

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
wrangler	Minor
@cloudflare/vite-plugin	Patch
@cloudflare/vitest-pool-workers	Patch

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commit: aafe866