refactor: move common/shaders/ to src/shaders/

Relocates shared WGSL shaders under src/ where all source code lives,
eliminating the top-level common/ directory.

- Update asset references in workspaces/main/assets.txt and workspaces/test/assets.txt
- Update docs: PROJECT_CONTEXT.md, ARCHITECTURE.md, WORKSPACE_SYSTEM.md, SHADER_REUSE_INVESTIGATION.md

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

1 files changed, 27 insertions, 0 deletions

diff --git a/src/shaders/math/color.wgsl b/src/shaders/math/color.wgsl
new file mode 100644
index 0000000..9352053
--- /dev/null
+++ b/src/shaders/math/color.wgsl
@@ -0,0 +1,27 @@
+// Common color space and tone mapping functions.
+
+// sRGB to Linear approximation
+// Note: Assumes input is in sRGB color space.
+fn sRGB(t: vec3f) -> vec3f {
+  return mix(1.055 * pow(t, vec3f(1.0/2.4)) - 0.055, 12.92 * t, step(t, vec3f(0.0031308)));
+}
+
+// ACES Filmic Tone Mapping (Approximate)
+// A common tone mapping algorithm used in games and film.
+fn aces_approx(v_in: vec3f) -> vec3f {
+  var v = max(v_in, vec3f(0.0));
+  v *= 0.6;
+  let a = 2.51;
+  let b = 0.03;
+  let c = 2.43;
+  let d = 0.59;
+  let e = 0.14;
+  return clamp((v * (a * v + b)) / (v * (c * v + d) + e), vec3f(0.0), vec3f(1.0));
+}
+
+// HSV to RGB conversion
+const hsv2rgb_K = vec4f(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
+fn hsv2rgb(c: vec3f) -> vec3f {
+  let p = abs(fract(c.xxx + hsv2rgb_K.xyz) * 6.0 - hsv2rgb_K.www);
+  return c.z * mix(hsv2rgb_K.xxx, clamp(p - hsv2rgb_K.xxx, vec3f(0.0), vec3f(1.0)), c.y);
+}