Replace custom CLI parser with System.CommandLine 2.0.8

src/Directory.Packages.props

@@ -23,6 +23,7 @@
     <PackageVersion Include="NUnit.ConsoleRunner" Version="3.20.1" />
     <PackageVersion Include="NUnit3TestAdapter" Version="6.2.0" />
     <PackageVersion Include="SSH.NET" Version="2025.1.0" />
+    <PackageVersion Include="System.CommandLine" Version="2.0.8" />
     <PackageVersion Include="System.Drawing.Common" Version="10.0.7" />
     <PackageVersion Include="System.Resources.Extensions" Version="10.0.7" />
     <PackageVersion Include="Vanara.Library" Version="5.0.4" />

src/LogExpert.UI/Services/FileOperationService/FileOperationService.cs

@@ -182,6 +182,19 @@ public LogWindow AddTempFileTab (string fileName, string title)
             return null;
         }
 
+        // Session files (.lxj) aren't logs — dispatch them to the project loader and
+        // continue with only the log files. Without this, the .lxj would be treated as
+        // a raw log line in the multi-file tab.
+        if (fileNames.Any(f => f.EndsWith(".lxj", StringComparison.OrdinalIgnoreCase)))
+        {
+            foreach (var sessionFile in fileNames.Where(f => f.EndsWith(".lxj", StringComparison.OrdinalIgnoreCase)))
+            {
+                _projectFileCallback(sessionFile, false);
+            }
+            var logs = fileNames.Where(f => !f.EndsWith(".lxj", StringComparison.OrdinalIgnoreCase)).ToArray();
+            return logs.Length > 0 ? AddMultiFileTab(logs) : null;
+        }
+
         EncodingOptions encodingOptions = new();
         FillDefaultEncodingFromSettings(encodingOptions);