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/water.frag.glsl

@@ -0,0 +1,37 @@
+// Name: Water
+// Author: diatribes
+#version 330 core
+precision highp float;
+
+out vec4 FragColor;
+in vec2 vUV;
+uniform vec2 iResolution;
+uniform float iTime;
+
+/*
+    -2 by @FabriceNeyret2
+
+    thanks!!  :D
+
+    If it doesn't display correctly, change line 17 "r/r" to "vec3(1)"
+
+*/
+
+void mainImage( out vec4 o, vec2 u ) {
+    float s=.002,i,n;
+    vec3 r = vec3(iResolution.xy, iResolution.x/iResolution.y);
+    vec3 p = vec3(0);
+    u = (u-r.xy/2.)/r.y-.3;
+    for(o *= i; i++ < 32. && s > .001;o += vec4(5,2,1,0)/max(length(u-.1), 0.001))
+        for (p += vec3(u*s,s),s = 1. + p.y,
+            n =.01; n < 1.;n+=n)
+            s += abs(dot(sin(p.z+iTime+p / n), vec3(1))) * n*.1;
+    o = tanh(o/5e2);
+}
+
+void main() {
+    vec2 fragCoordPixels = vUV * iResolution;
+    vec4 outColor;
+    mainImage(outColor, fragCoordPixels);
+    FragColor = outColor;
+}