revert to vanilla assets

public/assets/minecraft/shaders/core/screenquad.vsh

@@ -0,0 +1,11 @@
+#version 330
+
+out vec2 texCoord;
+
+void main() {
+    vec2 uv = vec2((gl_VertexID << 1) & 2, gl_VertexID & 2);
+    vec4 pos = vec4(uv * vec2(2, 2) + vec2(-1, -1), 0, 1);
+
+    gl_Position = pos;
+    texCoord = uv;
+}