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, 10 deletions

diff --git a/common/shaders/render/fullscreen_vs.wgsl b/common/shaders/render/fullscreen_vs.wgsl
deleted file mode 100644
index 507b892..0000000
--- a/common/shaders/render/fullscreen_vs.wgsl
+++ /dev/null
@@ -1,10 +0,0 @@
-// Common vertex shader for fullscreen post-processing effects.
-// Draws a single triangle that covers the entire screen.
-@vertex fn vs_main(@builtin(vertex_index) i: u32) -> @builtin(position) vec4f {
-    var pos = array<vec2f, 3>(
-        vec2f(-1, -1),
-        vec2f( 3, -1),
-        vec2f(-1,  3)
-    );
-    return vec4f(pos[i], 0.0, 1.0);
-}