Kotlin 2.0.0-RC1 support, bugfixes related to the consumption directory

### Consumer

- Fixed the directory not being able to be set to a default value (!15)
- Add an example to the directory setting's documentation (3d5e56dd, !17)
- Warn if multiple files with the same name are being imported and thus overwrite each other (26dd2837, !17)

### Producer

- Fixed crash when running under Kotlin 2.0.0-RC1 (#10, !23)

### Build and deployment

- Automated tests for multiple usage scenarii (!17)
- Simplify the demo, since they duplicate the automated tests (!17)

### Dependencies

- Gradle 8.7 (5d30cd88)
- Kotlin 2.0.0-RC1 (66672126)