[Bug]: Container machine docs disagree on the home directory path

The new container machine docs describe the home directory in two different ways.

### What I found

In `docs/container-machine.md`, the first section says:

```text
Your repo lives in $HOME on macOS and is mounted at /Users/ inside the container machine.
```

But the quickstart right below it says:

```bash
container machine run -n dev pwd # /home/ — your Mac home dir, mounted in
```

Those two paths point users in different directions:

- `/Users/` sounds like the macOS path is preserved inside the Linux machine
- `/home/` sounds like a normal Linux home directory

### What the code seems to do

The implementation and tests point to `/home/` as the machine user's home.

`Sources/Services/MachineAPIService/Client/MachineConfiguration.swift`:

```swift
public var home: String {
"/home/\(username)"
}
```

The CLI test also checks for that exact path:

```swift
#expect(home == "/home/\(hostUsername)", "HOME should be set to /home/")
```

### Expected

The docs should use one clear story for this.

Something like:

```text
Your macOS home is shared into the container machine and exposed as the Linux user's home at /home/.
```

That keeps the docs aligned with the code and avoids users looking for their files under `/Users/` inside the machine.

### Why this matters

Container machines are meant to feel like a persistent Linux dev environment. The first thing users will check is `pwd`, `$HOME`, and where their repo is mounted. If the docs mention both `/Users/` and `/home/`, it is easy to think the mount is broken when it is actually just the doc wording.

Start with docs/container-machine.md and compare its first section with the quickstart example. Use Sources/Services/MachineAPIService/Client/MachineConfiguration.swift and the cited CLI test to verify the documented home path. Done means the documentation consistently explains that the macOS home is exposed as /home/ inside the machine.

Written by the indexing model from the issue text.