Containers deploy gives opaque 403 'Authentication error' when account is on Free plan

## Summary

When deploying a Worker with `[[containers]]` config on a **Free plan** account, `wrangler deploy` returns a generic `ApiError: Forbidden` with `{ error: 'Authentication error' }` after the Docker image builds successfully. There's no indication that the actual issue is the account needs the **Workers Paid plan**.

## Steps to reproduce

1. Create a Cloudflare account on the Free plan
2. Configure `wrangler.toml` with a `[[containers]]` block
3. Create an API token with Workers Scripts Edit + Cloudflare Images Edit permissions
4. Run `wrangler deploy`

## Expected behavior

A clear error message like:
> "Containers requires the Workers Paid plan. Upgrade at https://dash.cloudflare.com/?to=/:account/workers/plans"

Or at minimum, mention "Containers" and "plan" in the error.

## Actual behavior

```
✘ [ERROR] ApiError: Forbidden

📎 It looks like you are authenticating Wrangler via a custom API token set in an environment variable.
Please ensure it has the correct permissions for this operation.

url: 'https://api.cloudflare.com/client/v4/accounts//containers/me',
status: 403,
statusText: 'Forbidden',
body: { error: 'Authentication error' },
```

The error suggests the API **token** is wrong, but the real issue is the **plan**. We spent significant time debugging token permissions (creating new tokens, adding various permission scopes) before discovering the plan requirement.

## Additional context

- The Docker image builds and tags successfully before the error occurs, so you don't hit this until the very end of a long build
- The "Cloudflare Images" permission in the token creator UI sounds like it might cover Containers, but it doesn't — this adds to the confusion
- wrangler 4.90.0