Podman: unable to upgrade to tcp, received 500

### What happened?

Since the update to 2.3.0 the crossplane cli is not working anymore in my setup.
Version 2.2.0 is running without any issues.
I am using podman with rootful setup.

### How can we reproduce it?

- Install podman 6.1.0
- Create rootful machine
- Try "crossplane composition render"
- Fail with:
```
2026-08-21T18:28:39+02:00 DEBUG Function container reachable on network {"network": "crossplane-render-9jnm6ht7", "address": "hardcore_hodgkin:9443"}
2026-08-21T18:28:39+02:00 DEBUG Running crossplane internal render in Docker {"image": "xpkg.crossplane.io/crossplane/crossplane:stable", "network": "crossplane-render-9jnm6ht7"}
crossplane: error: cannot render composite resource: crossplane internal render in Docker returned error with output: : failed to attach to container: unable to upgrade to tcp, received 500
```

### What environment did it happen in?

* Crossplane CLI version: 2.3.0 -> 2.5.0
* Platform (e.g., linux/amd64): macos arm64
* Crossplane version (if applicable):

Start at the `crossplane composition render` entry point and trace the internal render-in-Docker path that attaches to the function container. Reproduce with a rootful Podman machine and compare the failing container-attach behavior with the working 2.2.0 release; done means rendering succeeds on the reported Podman setup.

Written by the indexing model from the issue text.