fix: prevent LazyColumn crash on duplicate timestamps in V2X topic detail view

app/src/main/java/com/hawhamburg/micr0bu/ui/screens/MqttTopicViewerScreen.kt

@@ -18,6 +18,7 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.runtime.remember
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -329,7 +330,7 @@ private fun MessageDetailPane(
     }
 
     LazyColumn(state = listState, modifier = Modifier.fillMaxSize()) {
-        items(reversed, key = { "${it.topic}-${it.timestamp}" }) { msg ->
+        itemsIndexed(reversed, key = { index, msg -> "${msg.topic}-${msg.timestamp}-$index" }) { _, msg ->
             MessageRow(msg)
             HorizontalDivider(color = MaterialTheme.colorScheme.outline.copy(alpha = 0.2f))
         }