fix(ui): show only count in multiselect top bar title

Long localized strings like "ausgewählt" caused the title to wrap
onto a second line, making the top bar taller than intended.
Display the selection count as a bare number instead; the close
button already implies selection mode.

Preserves selection_count string resources for card accessibility labels.

Author: inventory69

android/app/src/main/java/dev/dettmer/simplenotes/ui/main/MainScreen.kt

@@ -664,8 +664,9 @@ private fun SelectionTopBar(
         },
         title = {
             Text(
-                text = stringResource(R.string.selection_count, selectedCount),
-                style = MaterialTheme.typography.titleLarge
+                text = selectedCount.toString(),
+                style = MaterialTheme.typography.titleLarge,
+                maxLines = 1
             )
         },
         actions = {