chore: remove deprecated horses, clubs, officials, and persons services

- Deleted obsolete modules related to horses, clubs, officials, and persons services, including their configurations, build files, and database provisioning scripts.
- Cleaned up associated references in the project structure (e.g., `settings.gradle.kts`).
- Removed unused database tables and Spring beans related to these domains.

Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>

frontend/features/zns-import-feature/src/jvmMain/kotlin/at/mocode/zns/feature/presentation/StammdatenImportScreen.kt

@@ -109,7 +109,7 @@ fun StammdatenImportScreen(
           horizontalArrangement = Arrangement.spacedBy(8.dp),
         ) {
           Icon(Icons.Default.Error, contentDescription = null, tint = MaterialTheme.colorScheme.error)
-          Text(state.errorMessage!!, color = MaterialTheme.colorScheme.onErrorContainer)
+          Text(state.errorMessage, color = MaterialTheme.colorScheme.onErrorContainer)
         }
       }
     }