feat(verein-feature): add Vereinsverwaltung module with screens, ViewModel, and integration

- Introduced `verein-feature` module for managing Vereine, including list, detail, and editor views using `MsMasterDetailLayout`.
- Added new domain models (`Verein`, `VereinStatus`) and integrated mock data for development.
- Registered the new feature in `settings.gradle.kts` and `DesktopMainLayout.kt`, including breadcrumb navigation and entry point.
- Updated `VeranstaltungenUebersichtV2` to add Vereine as a quick-access KPI tile.
- Removed unnecessary logout functionality and adjusted the root navigation for consistency.

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

frontend/features/verein-feature/build.gradle.kts

@@ -0,0 +1,32 @@
+/**
+ * Feature-Modul: Vereins-Verwaltung (Desktop-only)
+ */
+plugins {
+  alias(libs.plugins.kotlinMultiplatform)
+  alias(libs.plugins.composeMultiplatform)
+  alias(libs.plugins.composeCompiler)
+}
+
+group = "at.mocode.clients"
+version = "1.0.0"
+
+kotlin {
+  jvm()
+  sourceSets {
+    jvmMain.dependencies {
+      implementation(projects.frontend.core.designSystem)
+      implementation(projects.frontend.core.domain)
+      implementation(projects.frontend.core.navigation)
+      implementation(compose.desktop.currentOs)
+      implementation(compose.foundation)
+      implementation(compose.runtime)
+      implementation(compose.material3)
+      implementation(compose.ui)
+      implementation(compose.materialIconsExtended)
+      implementation(libs.bundles.kmp.common)
+      implementation(libs.koin.core)
+      implementation(libs.koin.compose)
+      implementation(libs.koin.compose.viewmodel)
+    }
+  }
+}