Added slang shaders for additional samples

shaders/slang/offscreen/quad.slang

@@ -0,0 +1,28 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+    float2 UV;
+};
+
+[[vk::binding(1, 0)]] Sampler2D samplerColor;
+
+[shader("vertex")]
+VSOutput vertexMain(uint VertexIndex: SV_VertexID)
+{
+    VSOutput output;
+    output.UV = float2((VertexIndex << 1) & 2, VertexIndex & 2);
+    output.Pos = float4(output.UV * 2.0f - 1.0f, 0.0f, 1.0f);
+    return output;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+    return samplerColor.Sample(input.UV);
+}