refactor: Migrate project to Material 3 Expressive Catalog

This commit renames the project from "Material 3 Expressive Demo" to "Material 3 Expressive Catalog". This includes updating namespaces, package names, and project configuration files.

Key changes:
- Renamed application and namespace from `com.cavin.material3expressivedemo` to `com.cavin.material3expressivecatalog`.
- Updated project name in `settings.gradle.kts` and `.idea/.name`.
- Renamed various files and updated their package declarations to reflect the new project name.
- Removed `DetailScreen.kt` and `DetailScreenViewModel.kt` as part of the refactor.
- Introduced `ContentScreen.kt` for generic content display.
- Added `ButtonGroupExample.kt` and related navigation for a new ButtonGroup component.
- Updated `HomeScreen.kt` to display items in a `LazyVerticalGrid` and navigate to examples, including the new `ButtonGroupExample`.
- Modified `AppNavigation.kt` to include the new `ButtonGroupRoute` and remove the old `DetailsRoute`.
- Updated `README.md` to reflect the project name change and remove previous boilerplate content.
- Added new inspection profile settings in `.idea/inspectionProfiles/Project_Default.xml`.