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, 83 deletions

diff --git a/common/shaders/render/raymarching_id.wgsl b/common/shaders/render/raymarching_id.wgsl
deleted file mode 100644
index d9f32b2..0000000
--- a/common/shaders/render/raymarching_id.wgsl
+++ /dev/null
@@ -1,83 +0,0 @@
-// Common functions for Signed Distance Field (SDF) raymarching with object ID.
-//
-// Required user-defined functions:
-//   - dfWithID(vec3f) -> RayMarchResult
-//
-// Requires constants from raymarching.wgsl:
-//   TOLERANCE, MAX_RAY_LENGTH, MAX_RAY_MARCHES, NORM_OFF
-#include "render/raymarching"
-
-// ============================================================================
-// Two-Pass Raymarching Support
-// ============================================================================
-// Design note: RayMarchResult is passed/returned by value (not pointer).
-// At 12 bytes (3×f32), return value optimization makes this efficient.
-// See doc/CODING_STYLE.md for rationale.
-
-struct RayMarchResult {
-    distance: f32,      // Distance to surface (MAX_RAY_LENGTH if miss)
-    distance_max: f32,  // Total distance marched (for fog/AO)
-    object_id: f32,     // Object identifier (0.0 = background)
-}
-
-// Raymarch with object ID tracking.
-fn rayMarchWithID(ro: vec3f, rd: vec3f, init: RayMarchResult) -> RayMarchResult {
-  var t = init.distance;
-  var result = init;
-
-  for (var i = 0; i < MAX_RAY_MARCHES; i++) {
-    if (t > MAX_RAY_LENGTH) {
-      result.distance = MAX_RAY_LENGTH;
-      result.distance_max = MAX_RAY_LENGTH;
-      break;
-    }
-    let sample = dfWithID(ro + rd * t);
-    if (sample.distance < TOLERANCE) {
-      result.distance = t;
-      result.distance_max = t;
-      result.object_id = sample.object_id;
-      break;
-    }
-    t += sample.distance;
-  }
-
-  return result;
-}
-
-// Reconstruct world position from stored result.
-fn reconstructPosition(ray: Ray, result: RayMarchResult) -> vec3f {
-  return ray.origin + ray.direction * result.distance;
-}
-
-// Normal calculation using dfWithID.
-fn normalWithID(pos: vec3f) -> vec3f {
-  let eps = vec2f(NORM_OFF, 0.0);
-  var nor: vec3f;
-  nor.x = dfWithID(pos + eps.xyy).distance - dfWithID(pos - eps.xyy).distance;
-  nor.y = dfWithID(pos + eps.yxy).distance - dfWithID(pos - eps.yxy).distance;
-  nor.z = dfWithID(pos + eps.yyx).distance - dfWithID(pos - eps.yyx).distance;
-  return normalize(nor);
-}
-
-// Shadow using stored intersection distance.
-fn shadowWithStoredDistance(lp: vec3f, ld: vec3f, stored_dist: f32) -> f32 {
-  let ds = 1.0 - 0.4;
-  var t = 0.01;
-  var nd = 1e6;
-  let soff = 0.05;
-  let smul = 1.5;
-  let MAX_SHD_MARCHES = 20;
-
-  for (var i = 0; i < MAX_SHD_MARCHES; i++) {
-    let p = lp + ld * t;
-    let d = dfWithID(p).distance;
-    if (d < TOLERANCE || t >= stored_dist) {
-      let sd = 1.0 - exp(-smul * max(t / stored_dist - soff, 0.0));
-      return select(mix(sd, 1.0, smoothstep(0.0, 0.025, nd)), sd, t >= stored_dist);
-    }
-    nd = min(nd, d);
-    t += ds * d;
-  }
-  let sd = 1.0 - exp(-smul * max(t / stored_dist - soff, 0.0));
-  return sd;
-}