upd: sync local changes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

source_code/Properties/AssemblyInfo.cs

@@ -0,0 +1,6 @@
+using System.Runtime.CompilerServices;
+
+// Exposes internal pure-math/parsing helpers of the Live2D mod to the game's
+// unit test project (tests/Cthangover.Tests). Internal members are the test
+// seam; public runtime API stays unchanged.
+[assembly: InternalsVisibleTo("Cthangover.Tests")]