Add FPS counter, VSync toggle, shader metadata system, and multi-pass infrastructure

- FPS counter in window title (updates every 500ms)
- F4 key toggles VSync on/off
- Shader metadata: Name and Author from comments
- iChannel metadata parsing for multi-pass support
- Base structures: ShaderBuffer, ShaderPass
- FBO/texture management functions
- Updated all 11 shaders with Name/Author metadata

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

shaders/remember.frag.glsl

@@ -0,0 +1,73 @@
+// Name: Remember
+// Author: diatribes
+// URL: https://www.shadertoy.com/view/tXSBDK
+#version 330 core
+precision highp float;
+
+out vec4 FragColor;
+in vec2 vUV;
+uniform vec2 iResolution;
+uniform float iTime;
+
+// fuzzy brain
+
+// Hash function to replace iChannel0 texture noise
+float hash12(vec2 p) {
+    vec3 p3 = fract(vec3(p.xyx) * .1031);
+    p3 += dot(p3, p3.yzx + 33.33);
+    return fract((p3.x + p3.y) * p3.z);
+}
+
+void mainImage(out vec4 o, vec2 u) {
+
+    vec3 q,p = vec3(iResolution.xy, iResolution.x / iResolution.y);
+
+    float i = 0.0, s,
+          // start the ray at a small random distance,
+          // this will reduce banding
+          // Replaced texelFetch(iChannel0, ...) with hash function
+          d = .125 * hash12(u),
+          t = iTime * .1;
+
+    // scale coords
+    u = (u+u-p.xy)/p.y;
+    if (abs(u.y) > .8) { o = vec4(0); return; }
+
+    // Initialize output color (out parameter must be initialized before use)
+    o = vec4(0.0);
+
+    for(; i<64.; i++) {
+
+        // shorthand for standard raymarch sample, then move forward:
+        // p = ro + rd * d, p.z + t
+        q = p = vec3(u * d, d + t*5.);
+        p.xy *= mat2(cos(.1*p.z+.1*t+vec4(0,33,11,0)));
+
+        q.xz = cos(q.xz);
+        p.z = cos(p.z) ;
+        // turbulence
+        for (s = 1.; s++ <6.;
+            q += sin(.6*t+p.zxy*.6),
+            p += sin(t+t+p.yzx*s)*.6);
+
+        // distance to spheres
+        d += s = .02 + abs(min(length(p+3.*sin(p.z*.5))-4., length(q-2.*sin(p.z*.4))-6.))*.2;
+
+        // color: 1.+cos so we don't go negative, cos(d+vec4(6,4,2,0)) samples from the palette
+        // divide by s for form and distance
+        // Clamp only the first term to prevent extreme overflow, leave second term free
+        vec4 brightTerm = min(.01*vec4(6,2,1,0)/max(length(u*sin(t+t+t)), 0.001), vec4(50.0));
+        o += brightTerm + 1. / s * length(u);
+
+    }
+
+    // tonemap and divide brightness
+    o = tanh(max(o /6e2 + dot(u,u)*.35, 0.));
+}
+
+void main() {
+    vec2 fragCoordPixels = vUV * iResolution;
+    vec4 outColor;
+    mainImage(outColor, fragCoordPixels);
+    FragColor = outColor;
+}