SSR not reflecting scene when ROUGHNESS>0

## Bevy version

main

If your bug is rendering-related, copy the adapter info that appears when you run Bevy.

```
2025-06-24T20:59:37.399107Z INFO bevy_diagnostic::system_information_diagnostics_plugin::internal: SystemInfo { os: "macOS 15.5 Sequoia", kernel: "24.5.0", cpu: "Apple M4 Max", core_count: "14", memory: "36.0 GiB" }
2025-06-24T20:59:37.494596Z INFO bevy_render::renderer: AdapterInfo { name: "Apple M4 Max", vendor: 0, device: 0, device_type: IntegratedGpu, driver: "", driver_info: "", backend: Metal }
```

## What you did
You can run the reproduction demo which I created to produce this screenshot:
https://github.com/seabassjh/bevy/blob/ssr-bug/examples/3d/ssr.rs

`cargo run --example ssr` -- I adapted this existing SSR example to demonstrate this bug which manifests with PBR spheres and no environment map / skybox.

## What went wrong

- what were you expecting?
SSR on all the spheres
- what actually happened?
SSR only on the spheres with 0 ROUGHNESS

## Additional information

Run `cargo run --example ssr` using the reproduction in examples/3d/ssr.rs and confirm the difference between zero and nonzero roughness on the PBR spheres. Then trace the SSR and PBR rendering behavior involved in that example; done means SSR appears on all spheres without an environment map or skybox.

Written by the indexing model from the issue text.