M1: Write MAML output to disk using updatable help folder structure (en-US/<module>-help.xml)

Implement the file writing logic for MAML output.

**M1 file layout**

```
<OutputRoot>/
  en-US/
    <ModuleName>-help.xml
```

**Definition of done**

* Output directory created if missing.
* `-Force` support (delete/overwrite existing output).
* No timestamps/random IDs in filenames.

**Acceptance checks**

* Integration test verifies correct file path(s) exist after generation.