added support for simultan downloads in files and talk, support for background downloads, enhanced loading in files with retry

lib/view/pages/files/data/file_type_icon.dart

@@ -19,6 +19,17 @@ IconData iconForFile(CacheableFile file) {
   return Icons.insert_drive_file_outlined;
 }
 
+/// Icon for a bare file name (no [CacheableFile] / MIME available), e.g. in the
+/// downloads overview. Falls back to a generic document icon.
+IconData iconForFileName(String name) {
+  final ext = _extensionOf(name);
+  if (ext != null) {
+    final byExt = _extensionIcons[ext];
+    if (byExt != null) return byExt;
+  }
+  return Icons.insert_drive_file_outlined;
+}
+
 String? _extensionOf(String name) {
   final dot = name.lastIndexOf('.');
   if (dot <= 0 || dot == name.length - 1) return null;