feat: show in-progress downloads with progress bar and cancel in DownloadsContent

- Add ActiveDownloadItem data class to represent a download in progress
- Add observeActiveDownloads() to MediaDownloadManager, polling the Media3
  download index every 500ms on Dispatchers.IO for reliable real-time progress
  (listener callbacks alone do not fire on every progress update)
- DownloadsViewModel exposes activeDownloads (StateFlow) and cancelDownload();
  the completed downloads flow filters out items currently in progress
- DownloadsContent shows a "Downloading" section with thumbnail, title,
  progress bar + percentage, and a cancel button above the completed grid

app/src/main/java/hu/bbara/purefin/app/home/ui/DownloadsContent.kt

@@ -4,23 +4,41 @@ import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.lazy.grid.GridCells
+import androidx.compose.foundation.lazy.grid.GridItemSpan
 import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
 import androidx.compose.foundation.lazy.grid.items
+import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.outlined.Close
 import androidx.compose.material.icons.outlined.Download
+import androidx.compose.material3.Card
+import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.LinearProgressIndicator
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
 import hu.bbara.purefin.common.ui.PosterCard
+import hu.bbara.purefin.common.ui.components.PurefinAsyncImage
+import hu.bbara.purefin.feature.shared.download.ActiveDownloadItem
 import hu.bbara.purefin.feature.shared.download.DownloadsViewModel
 
 @Composable
@@ -29,8 +47,11 @@ fun DownloadsContent(
     viewModel: DownloadsViewModel = hiltViewModel(),
 ) {
     val downloads = viewModel.downloads.collectAsState(emptyList())
+    val activeDownloads = viewModel.activeDownloads.collectAsState()
 
-    if (downloads.value.isEmpty()) {
+    val isEmpty = downloads.value.isEmpty() && activeDownloads.value.isEmpty()
+
+    if (isEmpty) {
         Column(
             modifier = modifier.fillMaxSize(),
             verticalArrangement = Arrangement.Center,
@@ -46,9 +67,9 @@ fun DownloadsContent(
                 text = "No downloads yet",
                 style = MaterialTheme.typography.titleMedium,
                 color = MaterialTheme.colorScheme.onSurfaceVariant,
-                modifier = Modifier
             )
         }
+        return
     }
 
     LazyVerticalGrid(
@@ -58,6 +79,37 @@ fun DownloadsContent(
         verticalArrangement = Arrangement.spacedBy(16.dp),
         modifier = modifier.background(MaterialTheme.colorScheme.background)
     ) {
+        if (activeDownloads.value.isNotEmpty()) {
+            item(span = { GridItemSpan(maxLineSpan) }) {
+                Text(
+                    text = "Downloading",
+                    style = MaterialTheme.typography.titleSmall,
+                    fontWeight = FontWeight.SemiBold,
+                    color = MaterialTheme.colorScheme.onBackground,
+                )
+            }
+            items(
+                items = activeDownloads.value,
+                key = { it.contentId },
+                span = { GridItemSpan(maxLineSpan) }
+            ) { item ->
+                DownloadingItemRow(
+                    item = item,
+                    onCancel = { viewModel.cancelDownload(it) }
+                )
+            }
+            if (downloads.value.isNotEmpty()) {
+                item(span = { GridItemSpan(maxLineSpan) }) {
+                    Text(
+                        text = "Downloaded",
+                        style = MaterialTheme.typography.titleSmall,
+                        fontWeight = FontWeight.SemiBold,
+                        color = MaterialTheme.colorScheme.onBackground,
+                        modifier = Modifier.padding(top = 8.dp)
+                    )
+                }
+            }
+        }
         items(downloads.value) { item ->
             PosterCard(
                 item = item,
@@ -67,5 +119,77 @@ fun DownloadsContent(
             )
         }
     }
-
+}
+
+@Composable
+private fun DownloadingItemRow(
+    item: ActiveDownloadItem,
+    onCancel: (String) -> Unit,
+) {
+    Card(
+        modifier = Modifier.fillMaxWidth(),
+        colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.surfaceVariant),
+        shape = RoundedCornerShape(12.dp)
+    ) {
+        Row(
+            modifier = Modifier.padding(12.dp),
+            verticalAlignment = Alignment.CenterVertically
+        ) {
+            PurefinAsyncImage(
+                model = item.imageUrl,
+                contentDescription = null,
+                contentScale = ContentScale.Crop,
+                modifier = Modifier
+                    .size(width = 44.dp, height = 66.dp)
+                    .clip(RoundedCornerShape(8.dp))
+            )
+            Column(
+                modifier = Modifier
+                    .weight(1f)
+                    .padding(horizontal = 12.dp)
+            ) {
+                Text(
+                    text = item.title,
+                    style = MaterialTheme.typography.bodyMedium,
+                    fontWeight = FontWeight.Medium,
+                    color = MaterialTheme.colorScheme.onSurface,
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis
+                )
+                if (item.subtitle.isNotEmpty()) {
+                    Text(
+                        text = item.subtitle,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        maxLines = 1,
+                        overflow = TextOverflow.Ellipsis
+                    )
+                }
+                Spacer(modifier = Modifier.height(6.dp))
+                Row(
+                    verticalAlignment = Alignment.CenterVertically,
+                    horizontalArrangement = Arrangement.spacedBy(8.dp)
+                ) {
+                    LinearProgressIndicator(
+                        progress = { item.progress / 100f },
+                        modifier = Modifier.weight(1f),
+                        color = MaterialTheme.colorScheme.primary,
+                        trackColor = MaterialTheme.colorScheme.outline.copy(alpha = 0.3f)
+                    )
+                    Text(
+                        text = "${item.progress.toInt()}%",
+                        style = MaterialTheme.typography.labelSmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant
+                    )
+                }
+            }
+            IconButton(onClick = { onCancel(item.contentId) }) {
+                Icon(
+                    imageVector = Icons.Outlined.Close,
+                    contentDescription = "Cancel download",
+                    tint = MaterialTheme.colorScheme.onSurfaceVariant
+                )
+            }
+        }
+    }
 }