feat(vr): add OpenComposite VR menu

package/Shaders/VR/InSceneOverlay.ps.hlsl

@@ -0,0 +1,17 @@
+// VR In-Scene Overlay Pixel Shader
+// Samples overlay texture with alpha blending support
+
+Texture2D shaderTexture : register(t0);
+SamplerState sampleType : register(s0);
+
+struct PS_INPUT
+{
+	float4 pos : SV_POSITION;
+	float2 uv : TEXCOORD0;
+};
+
+float4 main(PS_INPUT input) : SV_TARGET
+{
+	float4 color = shaderTexture.Sample(sampleType, input.uv);
+	return color;
+}

package/Shaders/VR/InSceneOverlay.vs.hlsl

@@ -0,0 +1,27 @@
+// VR In-Scene Overlay Vertex Shader
+// Simple pass-through shader for rendering overlay quad in VR
+
+cbuffer MatrixBuffer : register(b0)
+{
+	matrix wvp;
+};
+
+struct VS_INPUT
+{
+	float3 pos : POSITION;
+	float2 uv : TEXCOORD0;
+};
+
+struct PS_INPUT
+{
+	float4 pos : SV_POSITION;
+	float2 uv : TEXCOORD0;
+};
+
+PS_INPUT main(VS_INPUT input)
+{
+	PS_INPUT output;
+	output.pos = mul(float4(input.pos, 1.0f), wvp);
+	output.uv = input.uv;
+	return output;
+}