feat: add comprehensive logging for downloads debugging

Added extensive logging throughout DownloadsProvider and DownloadsScreen
to diagnose why downloads screen appears empty.

DownloadsProvider.refreshDownloads():
- 📥 Log function call
- 📥 Log state changes (loading, error)
- 📥 Log TorrentPlatformService.getAllDownloads() call
- 📥 Log number of torrents received
- 📥 Log each torrent processing with index
- 📥 Log success/failure for each torrent info fetch
- 📥 Log final torrents count
- 📥 Log completion or error state

DownloadsScreen.initState() and Consumer:
- 📥 Log initState call
- 📥 Log postFrameCallback execution
- 📥 Log Consumer builder invocations
- 📥 Log provider state (isLoading, error, torrents.length)
- 📥 Log which UI is displayed:
  * CircularProgressIndicator
  * ErrorDisplay
  * Empty state message
  * Torrent list with count

All logs prefixed with 📥 for easy filtering in logcat.

Example output:
---
📥 DownloadsScreen: initState() called
📥 DownloadsScreen: postFrameCallback, calling refreshDownloads()
📥 DownloadsProvider: refreshDownloads() called
📥 Setting loading=true, error=null
📥 Calling TorrentPlatformService.getAllDownloads()...
📥 Got 0 torrents from platform service
📥 Cleared _torrents list
📥 Final torrents count: 0
📥 Setting loading=false
📥 ✅ refreshDownloads() completed successfully
📥 DownloadsScreen: Consumer builder called
📥   isLoading: false
📥   error: null
📥   torrents.length: 0
📥   → Showing empty state

This will help identify:
- Is refreshDownloads being called?
- Does TorrentPlatformService return any data?
- Are torrents parsed correctly?
- Is the correct UI state shown?
- Where does the process fail?

Usage:
Run app → Open Downloads screen → Check logcat for 📥 logs

lib/presentation/screens/downloads/downloads_screen.dart

@@ -40,13 +40,20 @@ class _DownloadsScreenState extends State<DownloadsScreen> {
       ),
       body: Consumer<DownloadsProvider>(
         builder: (context, provider, child) {
+          print('📥 DownloadsScreen: Consumer builder called');
+          print('📥   isLoading: ${provider.isLoading}');
+          print('📥   error: ${provider.error}');
+          print('📥   torrents.length: ${provider.torrents.length}');
+          
           if (provider.isLoading) {
+            print('📥   → Showing CircularProgressIndicator');
             return const Center(
               child: CircularProgressIndicator(),
             );
           }
 
           if (provider.error != null) {
+            print('📥   → Showing ErrorDisplay');
             return ErrorDisplay(
               title: 'Ошибка загрузки торрентов',
               error: provider.error!,
@@ -58,6 +65,7 @@ class _DownloadsScreenState extends State<DownloadsScreen> {
           }
 
           if (provider.torrents.isEmpty) {
+            print('📥   → Showing empty state');
             return Center(
               child: Column(
                 mainAxisAlignment: MainAxisAlignment.center,
@@ -87,6 +95,7 @@ class _DownloadsScreenState extends State<DownloadsScreen> {
             );
           }
 
+          print('📥   → Showing ${provider.torrents.length} torrents in list');
           return RefreshIndicator(
             onRefresh: () async {
               await provider.refreshDownloads();