Increase session timeout for large transaction uploads

Extend session IOTimeout to 5 minutes to accommodate serialization and storage of large transaction preview datasets (e.g., 2800+ transactions).

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Co-Authored-By: Claude <noreply@anthropic.com>

MoneyMap/Program.cs

@@ -17,6 +17,7 @@ builder.Services.AddSession(options =>
     options.IdleTimeout = TimeSpan.FromMinutes(30);
     options.Cookie.HttpOnly = true;
     options.Cookie.IsEssential = true;
+    options.IOTimeout = TimeSpan.FromMinutes(5); // Increase timeout for large data
 });
 
 // Add the new services here