refactor(effects): co-locate effect WGSL shaders with their .h/.cc in src/effects/

Move 13 effect-specific shaders from workspaces/main/shaders/ to src/effects/
so each effect's .h, .cc, and .wgsl are together. Update assets.txt paths in
both main and test workspaces. Update EFFECT_WORKFLOW.md to reflect new location.
Shared/reusable snippets remain in src/shaders/.

handoff(Gemini): shaders moved; src/effects/ now has .h, .cc, and .wgsl per effect.

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

1 files changed, 33 insertions, 0 deletions

diff --git a/src/effects/gaussian_blur.wgsl b/src/effects/gaussian_blur.wgsl
new file mode 100644
index 0000000..68e0720
--- /dev/null
+++ b/src/effects/gaussian_blur.wgsl
@@ -0,0 +1,33 @@
+// 5x5 gaussian blur
+
+@group(0) @binding(0) var smplr: sampler;
+@group(0) @binding(1) var txt: texture_2d<f32>;
+
+#include "common_uniforms"
+#include "render/fullscreen_vs"
+
+struct GaussianBlurParams {
+    strength: f32,
+    strength_audio: f32,
+    stretch: f32,  // dir_y / dir_x
+    _pad: f32,
+};
+
+@group(0) @binding(2) var<uniform> uniforms: CommonUniforms;
+@group(0) @binding(3) var<uniform> params: GaussianBlurParams;
+
+@fragment fn fs_main(@builtin(position) p: vec4f) -> @location(0) vec4f {
+    // Parameterized strength + dramatic beat pulsation
+    let pulse = 1.0 + uniforms.audio_intensity * params.strength_audio;  // Pulsate beat
+    let size = params.strength * pulse;
+    let dir = vec2f(1., params.stretch) * size / uniforms.resolution.x;
+
+    let uv = p.xy / uniforms.resolution;
+    var res = vec4f(0.0);
+    for (var x: f32 = -2.0; x <= 2.0; x += 1.0) {
+        for (var y: f32 = -2.0; y <= 2.0; y += 1.0) {
+            res += textureSample(txt, smplr, uv + vec2f(x, y) * dir);
+        }
+    }
+    return res * (1. / 25.0);
+}