[Bug]: `container cp` fails with "invalid path given" when a path contains a colon

### Steps to reproduce

1. Create a file whose name contains a colon inside a container (common with ISO-8601 timestamps):
```
container run -d --name cpbox alpine \
sh -c 'echo hi > "/var/log/app-2026-07-20T10:30:00.log"; sleep 300'
```
2. Copy it out:
```
container cp "cpbox:/var/log/app-2026-07-20T10:30:00.log" ./out.log
```

### Current behavior

```
Error: invalid path given: cpbox:/var/log/app-2026-07-20T10:30:00.log
```

The file exists in the container (a colon is a legal character in a Linux path); only the reference parsing fails. Copying a file whose name contains no colon works.

### Expected behavior

The file is copied out — matching `docker cp`, which splits the `container:path` reference on the first colon only.

### Root cause

`Application.ContainerCopy.parsePathRef` splits the reference on *every* colon (`components(separatedBy: ":")`) and rejects anything that produces more than two parts. Any colon in the path (after the id) makes the parse fail. It should split on the first colon only, since a container id cannot contain a path separator.

### Environment

- container 1.1.0
- macOS 26.5 (Tahoe), Apple Silicon

Start at Application.ContainerCopy.parsePathRef, which the report identifies as splitting container references on every colon. Reproduce the issue with the provided `container cp` command using a colon-containing path, then verify that the reference is split only at the first colon and the file is copied successfully.

Written by the indexing model from the issue text.