feat: expose legacy launcher configuration workflow

tests/Launcher.Next.Tests/PlantDiscoveryTests.cs

@@ -0,0 +1,18 @@
+using Launcher.Next.Autodesk;
+using Xunit;
+
+namespace Launcher.Next.Tests;
+
+public sealed class PlantDiscoveryTests
+{
+    private sealed class Registry(string? install) : IRegistryReader
+    { public object? GetValue(string path,string name)=>path.Contains("ACAD-9117",StringComparison.Ordinal)&&name=="InstallDir"?install:null; }
+
+    [Fact]
+    public void Plant2026DiscoveryUsesPlantSpecificRegistryKey()
+    {
+        var directory=Path.Combine(Path.GetTempPath(),Guid.NewGuid().ToString("N"));Directory.CreateDirectory(Path.Combine(directory,"PLNT3D"));File.WriteAllBytes(Path.Combine(directory,"acad.exe"),[]);
+        try { var product=new PlantProductDiscovery(new Registry(directory)).DiscoverPlant3D(2026);Assert.NotNull(product);Assert.Equal("2026",product!.ProductVersion);Assert.Equal(Path.Combine(directory,"acad.exe"),product.ExecutablePath); }
+        finally { Directory.Delete(directory,true); }
+    }
+}