[code][fix] improvements for LAN 202503

- more robust client <-> server connection
  - new client event: DownloadGameFilesFailed
  - 3 seconds to reconnect
  - retry forever if server is gone and never lose a UI request

- code cleanup here and there (mostly server)

crates/lanspread-tauri-deno-ts/src/App.tsx

@@ -48,13 +48,37 @@ const App = () => {
         }
     };
 
+    useEffect(() => {
+        // Listen for game-download-failed events specifically
+        const setupDownloadFailedListener = async () => {
+            const unlisten = await listen('game-download-failed', (event) => {
+                const game_id = event.payload as string;
+                console.log(`❌ game-download-failed ${game_id} event received`);
+                setGameItems(prev => prev.map(item => item.id === game_id
+                    ? {...item, install_status: InstallStatus.NotInstalled}
+                    : item));
+
+                // Convert to string explicitly and verify it's not empty
+                const pathString = String(gameDir);
+                if (!pathString) {
+                    console.error('gameDir is empty before invoke!');
+                    return;
+                }
+                invoke('update_game_directory', { path: pathString })
+                    .catch(error => console.error('❌ Error updating game directory:', error));
+            });
+            return unlisten;
+        };
+
+        setupDownloadFailedListener();
+    }, [gameDir]);
+
     useEffect(() => {
         // Listen for game-unpack-finished events specifically
         const setupUnpackListener = async () => {
             const unlisten = await listen('game-unpack-finished', (event) => {
                 const game_id = event.payload as string;
                 console.log(`🗲 game-unpack-finished ${game_id} event received`);
-                console.log('Current gameDir in listener:', gameDir); // Add this log
                 setGameItems(prev => prev.map(item => item.id === game_id
                     ? {...item, install_status: InstallStatus.Installed}
                     : item));