### feat: verbessere Validierungs- und Draft-Funktionalität im Wizard

- Entferne `onNavigateToVeranstalterNeu` aus `EventWizardScreen` und zugehörigen Komponenten.
- Füge persistente Speicherung für Drafts über `DraftStore` hinzu (JSON für JVM, No-op für Wasm).
- Ergänze WizardScaffold um `errorSummary` zur Anzeige von Validierungsfehlern.
- Bereinige und optimiere Schritt-Logik in `EventWizardViewModel`.

frontend/core/wizard/build.gradle.kts

@@ -13,6 +13,9 @@ group = "at.mocode.frontend.core"
 version = "1.0.0"
 
 kotlin {
+  compilerOptions {
+    freeCompilerArgs.add("-Xexpect-actual-classes")
+  }
   jvm()
 
   wasmJs {

frontend/core/wizard/src/commonMain/kotlin/at/mocode/frontend/core/wizard/draft/DraftStore.kt

@@ -1,15 +1,14 @@
 package at.mocode.frontend.core.wizard.draft
 
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class DraftEntry(val version: Int, val stepId: String)
+
 /**
- * Minimaler DraftStore (MVP): in‑Memory, versioniert per Key. Persistenz folgt später.
+ * Persistenter DraftStore.
  */
-object DraftStoreMemory {
-  private data class Entry(val version: Int, val stepId: String)
-  private val store = mutableMapOf<String, Entry>()
-
-  fun save(flowKey: String, version: Int, stepId: String) {
-    store[flowKey] = Entry(version, stepId)
-  }
-
-  fun load(flowKey: String): Pair<Int, String>? = store[flowKey]?.let { it.version to it.stepId }
+expect object DraftStore {
+  fun save(flowKey: String, version: Int, stepId: String)
+  fun load(flowKey: String): Pair<Int, String>?
 }

frontend/core/wizard/src/commonMain/kotlin/at/mocode/frontend/core/wizard/ui/WizardScaffold.kt

@@ -27,6 +27,7 @@ fun WizardScaffold(
   onBack: () -> Unit,
   onNext: () -> Unit,
   onSaveDraft: (() -> Unit)? = null,
+  errorSummary: String? = null,
   nextLabel: String = "Weiter",
   backLabel: String = "Zurück",
   finishLabel: String = "Fertig",
@@ -80,6 +81,21 @@ fun WizardScaffold(
 
       Spacer(Modifier.height(12.dp))
 
+      if (errorSummary != null) {
+        Surface(
+          color = MaterialTheme.colorScheme.errorContainer,
+          shape = MaterialTheme.shapes.small,
+          modifier = Modifier.fillMaxWidth().padding(bottom = 8.dp)
+        ) {
+          Text(
+            text = errorSummary,
+            color = MaterialTheme.colorScheme.onErrorContainer,
+            style = MaterialTheme.typography.bodySmall,
+            modifier = Modifier.padding(8.dp)
+          )
+        }
+      }
+
       // Footer: Actions
       Row(
         modifier = Modifier.fillMaxWidth(),

frontend/core/wizard/src/jvmMain/kotlin/at/mocode/frontend/core/wizard/draft/DraftStore.jvm.kt

@@ -0,0 +1,31 @@
+package at.mocode.frontend.core.wizard.draft
+
+import kotlinx.serialization.json.Json
+import java.io.File
+
+actual object DraftStore {
+  private val draftDir = File("drafts").apply { if (!exists()) mkdirs() }
+  private val json = Json { prettyPrint = true; ignoreUnknownKeys = true }
+
+  actual fun save(flowKey: String, version: Int, stepId: String) {
+    try {
+      val file = File(draftDir, "${flowKey}.json")
+      val entry = DraftEntry(version, stepId)
+      file.writeText(json.encodeToString(entry))
+    } catch (e: Exception) {
+      println("DraftStore: Error saving draft for $flowKey: ${e.message}")
+    }
+  }
+
+  actual fun load(flowKey: String): Pair<Int, String>? {
+    val file = File(draftDir, "${flowKey}.json")
+    if (!file.exists()) return null
+    return try {
+      val entry = json.decodeFromString<DraftEntry>(file.readText())
+      entry.version to entry.stepId
+    } catch (e: Exception) {
+      println("DraftStore: Error loading draft for $flowKey: ${e.message}")
+      null
+    }
+  }
+}

frontend/core/wizard/src/jvmMain/kotlin/at/mocode/frontend/core/wizard/ui/WizardHotkeys.kt

@@ -18,6 +18,7 @@ fun WizardScaffoldWithHotkeys(
   onBack: () -> Unit,
   onNext: () -> Unit,
   onSaveDraft: (() -> Unit)? = null,
+  errorSummary: String? = null,
   nextLabel: String = "Weiter",
   backLabel: String = "Zurück",
   finishLabel: String = "Fertig",
@@ -54,6 +55,7 @@ fun WizardScaffoldWithHotkeys(
       onBack = onBack,
       onNext = onNext,
       onSaveDraft = onSaveDraft,
+      errorSummary = errorSummary,
       nextLabel = nextLabel,
       backLabel = backLabel,
       finishLabel = finishLabel,

frontend/core/wizard/src/wasmJsMain/kotlin/at/mocode/frontend/core/wizard/draft/DraftStore.wasmJs.kt

@@ -0,0 +1,9 @@
+package at.mocode.frontend.core.wizard.draft
+
+actual object DraftStore {
+  actual fun save(flowKey: String, version: Int, stepId: String) {
+    // No-op for WasmJs MVP
+  }
+
+  actual fun load(flowKey: String): Pair<Int, String>? = null
+}