Enhance video file handling in file explorer; implement viewer session for authenticated URL and improve error handling for missing file ID.

b0esche_cloud/lib/pages/file_explorer.dart

@@ -901,15 +901,26 @@ class _FileExplorerState extends State<FileExplorer> {
           if (file.type == FileType.folder) {
             context.read<FileBrowserBloc>().add(NavigateToFolder(file.path));
           } else if (isVideo) {
-            // Open video files in video viewer
+            // Open video files in video viewer - use viewer session for authenticated URL
-            final videoUrl = await getIt<FileService>().getDownloadUrl(
+            if (file.id == null || file.id!.isEmpty) {
+              ScaffoldMessenger.of(context).showSnackBar(
+                const SnackBar(content: Text('Error: File ID is missing')),
+              );
+              return;
+            }
+            try {
+              final session = await getIt<FileService>().requestViewerSession(
                 widget.orgId,
-              file.path,
+                file.id!,
               );
-            _showVideoViewer(
+              _showVideoViewer(file.name, session.viewUrl.toString());
-              file.name,
+            } catch (e) {
-              '${getIt<FileService>().baseUrl}$videoUrl',
+              if (mounted) {
+                ScaffoldMessenger.of(context).showSnackBar(
+                  SnackBar(content: Text('Error loading video: $e')),
                 );
+              }
+            }
           } else {
             if (file.id == null || file.id!.isEmpty) {
               ScaffoldMessenger.of(context).showSnackBar(