bitwarden-nginx trying to use port 80 fails to start

### Steps To Reproduce

1. Deploy Bitwarden
2. `./bitwarden start`
3. Run `docker ps`
4. See the `bitwarden-nginx` container fail to start and try to bind to port `80`

### Expected Result

It just works, bitwarden-nginx stays running and I can access Bitwarden.

### Actual Result

As soon as it starts:
```
ghcr.io/bitwarden/nginx:2025.8.1 "/entrypoint.sh" 14 minutes ago Up Less than a second (health: starting) 80/tcp, 8443/tcp, 0.0.0.0:5178->8080/tcp, [::]:5178->8080/tcp bitwarden-nginx
```

After a few seconds:
```
ghcr.io/bitwarden/nginx:2025.8.1 "/entrypoint.sh" 11 seconds ago Restarting (1) 2 seconds ago bitwarden-nginx
```

Nginx error logs:
```
2025/09/10 16:18:31 [emerg] 1#1: open() "/etc/nginx/conf.d/default.conf" failed (13: Permission denied) in /etc/nginx/nginx.conf:148
2025/09/10 16:18:38 [emerg] 1#1: open() "/etc/nginx/conf.d/default.conf" failed (13: Permission denied) in /etc/nginx/nginx.conf:148
2025/09/10 16:18:51 [emerg] 1#1: open() "/etc/nginx/conf.d/default.conf" failed (13: Permission denied) in /etc/nginx/nginx.conf:148
2025/09/10 16:19:17 [emerg] 1#1: open() "/etc/nginx/conf.d/default.conf" failed (13: Permission denied) in /etc/nginx/nginx.conf:148
```

### Screenshots or Videos

_No response_

### Additional Context

I'm using the default configuration for all the containers.

### Githash Version

236027fc

### Environment Details

- Operating System: Debian 12
- Environment: Docker

### Database Image

ghcr.io/bitwarden/mssql:2025.8.1

### Issue-Link

https://github.com/bitwarden/server/issues/2480

### Issue Tracking Info

- [x] I understand that work is tracked outside of Github. A PR will be linked to this issue should one be opened to address it, but Bitwarden doesn't use fields like "assigned", "milestone", or "project" to track progress.