polish: explain skipped duplicates on the import-complete screen

The import de-dups by UID against the target calendar (idempotent restore),
so re-importing events already present shows a low 'Added' count. Add a note
under the title when any were skipped so the outcome doesn't read as broken.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/src/main/java/de/jeanlucmakiola/calendula/ui/imports/ImportScreen.kt

@@ -48,6 +48,7 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.graphicsLayer
 import androidx.compose.ui.semantics.clearAndSetSemantics
 import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.res.pluralStringResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
@@ -198,6 +199,15 @@ private fun DoneContent(state: ImportUiState.Done, onClose: () -> Unit) {
             style = MaterialTheme.typography.headlineSmall,
             color = MaterialTheme.colorScheme.onSurface,
         )
+        if (state.summary.skippedDuplicate > 0) {
+            Spacer(Modifier.height(8.dp))
+            Text(
+                stringResource(R.string.import_done_dedup_note),
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                textAlign = TextAlign.Center,
+            )
+        }
         Spacer(Modifier.height(24.dp))
         Row(
             Modifier.fillMaxWidth(),