added barebones ui rendering

Shaders/ui.frag

@@ -0,0 +1,16 @@
+#version 440 core
+
+in vec2 TexCoord;
+in vec4 Color;
+
+out vec4 FragColor;
+
+uniform sampler2D uTexture; // Ensure this name matches C# exactly
+
+void main() 
+{
+    vec4 texColor = texture(uTexture, TexCoord);
+    
+    // If you don't use texColor, uTexture gets deleted by the compiler
+    FragColor = texColor * Color;
+}