add LICENSE, shaders, Cargo.lock, and AUR package

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

shaders/example.frag

@@ -0,0 +1,23 @@
+// Example Shadertoy-style fragment shader for gpupaper.
+// Demonstrates use of 'time' and 'resolution' uniforms.
+//
+// Usage: gpupaper HDMI-A-1 shaders/example.frag
+
+uniform vec2 resolution;
+uniform float time;
+
+void mainImage(out vec4 fragColor, in vec2 fragCoord) {
+    vec2 uv = fragCoord / resolution;
+
+    // Animated gradient
+    float r = 0.5 + 0.5 * sin(time * 0.7 + uv.x * 3.0);
+    float g = 0.5 + 0.5 * sin(time * 0.5 + uv.y * 3.0 + 2.094);
+    float b = 0.5 + 0.5 * sin(time * 0.3 + (uv.x + uv.y) * 3.0 + 4.189);
+
+    // Vignette
+    vec2 centered = uv - 0.5;
+    float vignette = 1.0 - dot(centered, centered) * 2.0;
+    vignette = clamp(vignette, 0.0, 1.0);
+
+    fragColor = vec4(vec3(r, g, b) * vignette, 1.0);
+}