Move VBS_SDK ThirdParty under Source/

Why: Epic's own engine layout puts third-party libraries under
Engine/Source/ThirdParty/, treating them as compile-time inputs
alongside the modules. Aligning the plugin with this convention keeps
all build inputs (modules + third-party) self-contained under Source/.

- Rename Plugins/PS_ViveVBS/ThirdParty/ -> Plugins/PS_ViveVBS/Source/ThirdParty/.
- Update SdkRoot in Build.cs to Path.Combine(PluginDirectory, "Source", "ThirdParty", "VBS_SDK").
- Update FilterPlugin.ini paths.

Validated by clean rebuilds of Editor and Game Win64 Development
targets, both exit 0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Unreal/PS_ViveVBS/Plugins/PS_ViveVBS/Config/FilterPlugin.ini

@@ -2,5 +2,5 @@
 ; This section lists additional files which will be packaged along with your plugin. Paths should be listed relative to the root plugin directory, and
 ; may include "...", "*", and "?" wildcards to match directories, files, and individual characters respectively.
 
-/ThirdParty/VBS_SDK/include/...
+/Source/ThirdParty/VBS_SDK/include/...
-/ThirdParty/VBS_SDK/Win64/...
+/Source/ThirdParty/VBS_SDK/Win64/...

Unreal/PS_ViveVBS/Plugins/PS_ViveVBS/Source/ViveVBS/ViveVBS.Build.cs

@@ -23,7 +23,7 @@ public class ViveVBS : ModuleRules
 
 		if (Target.Platform == UnrealTargetPlatform.Win64)
 		{
-			string SdkRoot    = Path.Combine(PluginDirectory, "ThirdParty", "VBS_SDK");
+			string SdkRoot    = Path.Combine(PluginDirectory, "Source", "ThirdParty", "VBS_SDK");
 			string IncludeDir = Path.Combine(SdkRoot, "include");
 			string Win64Dir   = Path.Combine(SdkRoot, "Win64");