Multi-line permanent progress doesn't overwrite temporary progress

### Bug Description

I assumed it was possible to pass multi-line strings to `emit.progress`. At least, craft-application does it. However, the first line doesn't overwrite the existing progress line if it was longer.

### To Reproduce

```python
from craft_cli import EmitterMode, emit

emit.init(EmitterMode.BRIEF, appname="testcraft", greeting="Greeting")
emit.progress("foo foo foo")
emit.progress("bar\nbar", permanent=True)
```
Expected output:
```
bar
bar
```
Actual output:
```
bar foo foo
bar
```

### part yaml

```shell

```

### Relevant log output

```shell
2025-08-11 15:02:50.183 Greeting
2025-08-11 15:02:50.183 foo foo foo
2025-08-11 15:02:50.183 bar
bar
```

Run the Python reproduction from the issue and inspect the implementation behind emit.progress, especially permanent multi-line output and temporary-line clearing. Confirm the behavior with the shown input; done means the first line of the permanent message fully replaces the longer temporary progress line, producing exactly two lines: bar and bar.

Written by the indexing model from the issue text.