feat(zns-import): DAT-Dateisupport hinzugefügt, Fehlerbehebung und UI-Anpassungen

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

frontend/shells/meldestelle-desktop/src/jvmMain/kotlin/at/mocode/desktop/v2/VeranstaltungScreens.kt

@@ -1587,7 +1587,11 @@ fun ZnsImportWizardSection(
     Column(modifier = Modifier.padding(16.dp), verticalArrangement = Arrangement.spacedBy(12.dp)) {
       Row(verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(8.dp)) {
         Icon(Icons.Default.CloudUpload, contentDescription = null, tint = MaterialTheme.colorScheme.primary)
-        Text("ZNS-Stammdaten Import (ZIP)", style = MaterialTheme.typography.titleMedium, fontWeight = FontWeight.Bold)
+        Text(
+          "ZNS-Stammdaten Import (ZIP/DAT)",
+          style = MaterialTheme.typography.titleMedium,
+          fontWeight = FontWeight.Bold
+        )
         Spacer(Modifier.weight(1f))
         if (state.isFinished || state.errorMessage != null) {
           TextButton(onClick = onReset) {
@@ -1609,14 +1613,14 @@ fun ZnsImportWizardSection(
             value = state.selectedFilePath ?: "",
             onValueChange = {},
             readOnly = true,
-            placeholder = { Text("ZNS.zip auswählen...") },
+            placeholder = { Text("ZNS-Datei auswählen (.zip, .dat)...") },
             modifier = Modifier.weight(1f),
             singleLine = true,
             textStyle = MaterialTheme.typography.bodySmall
           )
           Button(
             onClick = {
-              val path = pickZipFile()
+              val path = pickZnsFile()
               if (path != null) onFileSelect(path)
             },
             enabled = !state.isUploading
@@ -1714,10 +1718,10 @@ fun ZnsImportWizardSection(
   }
 }
 
-private fun pickZipFile(): String? {
+private fun pickZnsFile(): String? {
   val chooser = JFileChooser()
-  chooser.dialogTitle = "ZNS.zip auswählen"
-  chooser.fileFilter = FileNameExtensionFilter("ZIP-Archiv (*.zip)", "zip")
+  chooser.dialogTitle = "ZNS-Datei auswählen"
+  chooser.fileFilter = FileNameExtensionFilter("ZNS Dateien (*.zip, *.dat)", "zip", "dat")
   chooser.isAcceptAllFileFilterUsed = false
   val result = chooser.showOpenDialog(null)
   return if (result == JFileChooser.APPROVE_OPTION) chooser.selectedFile.absolutePath else null