Count the downloads under each header instead of count the number of headers (#7990)

app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadController.kt

@@ -25,6 +25,7 @@ import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.material3.rememberTopAppBarState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -106,6 +107,9 @@ class DownloadController :
     override fun ComposeContent() {
         val context = LocalContext.current
         val downloadList by presenter.state.collectAsState()
+        val downloadCount by remember {
+            derivedStateOf { downloadList.sumOf { it.subItems.size } }
+        }
 
         val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior(rememberTopAppBarState())
         var fabExpanded by remember { mutableStateOf(true) }
@@ -142,10 +146,10 @@ class DownloadController :
                                 modifier = Modifier.weight(1f, false),
                                 overflow = TextOverflow.Ellipsis,
                             )
-                            if (downloadList.isNotEmpty()) {
+                            if (downloadCount > 0) {
                                 val pillAlpha = if (isSystemInDarkTheme()) 0.12f else 0.08f
                                 Pill(
-                                    text = "${downloadList.size}",
+                                    text = "$downloadCount",
                                     modifier = Modifier.padding(start = 4.dp),
                                     color = MaterialTheme.colorScheme.onBackground
                                         .copy(alpha = pillAlpha),