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, 0 insertions, 14 deletions

diff --git a/common/shaders/math/utils.wgsl b/common/shaders/math/utils.wgsl
deleted file mode 100644
index c75cb66..0000000
--- a/common/shaders/math/utils.wgsl
+++ /dev/null
@@ -1,14 +0,0 @@
-// General-purpose math utility functions.
-
-// Returns a 2x2 rotation matrix.
-fn rot(a: f32) -> mat2x2f {
-  let c = cos(a);
-  let s = sin(a);
-  return mat2x2f(c, s, -s, c);
-}
-
-// Fast approximation of tanh.
-fn tanh_approx(x: f32) -> f32 {
-  let x2 = x * x;
-  return clamp(x * (27.0 + x2) / (27.0 + 9.0 * x2), -1.0, 1.0);
-}