- Added `pferde-feature` module for managing horses, including list, detail, and editing views.
- Implemented `MsMasterDetailLayout` for PferdeScreen, integrating `MsDataTable`, `MsFilterBar`, and `MsActionToolbar`.
- Defined domain models (`Pferd`, `Geschlecht`, `PferdeStatus`) with mock data support.
- Updated roadmap to mark `Pferde-Verwaltung (MVP)` as complete.
- Registered the new module in `settings.gradle.kts` and `meldestelle-desktop` build configuration.
- Added previews for Pferde and Reiter components to support IDE render.
Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>