Support per-host SSH port configuration for servers and accessories

Hi team,

I'm trying to deploy to two different servers:

* `web` goes to **VPS1**, using **default SSH port 22**
* `accessories.db` goes to **VPS2**, using **custom SSH port 10234**

My current `deploy.yml` looks like this:

```yaml
servers:
web:
hosts:
- xx.xx.xx.xx

accessories:
db:
image: library/postgres:17.4
host: xx.xx.xx.xx
```

But I don't see a way to specify different SSH ports for each host.
Setting a global `ssh.port` affects all hosts, which doesn't work in this case.

**Question:**
Does Kamal currently support this kind of setup (different SSH ports per host)? If not, could it be supported in the future?

Thanks!

Start with the deploy.yml servers and accessories host definitions, then trace how the global ssh.port setting is applied. Done means web can use the default port while accessories.db uses port 10234, without changing the port for other hosts; no specific source file or test is named in the issue.

Written by the indexing model from the issue text.