feat: Implement workspace system (Task #77)

Self-contained workspaces for parallel demo development.

Structure:
- workspaces/main,test - Demo-specific resources
- assets/common - Shared resources
- workspace.cfg - Configuration per workspace

CMake integration:
- DEMO_WORKSPACE option (defaults to main)
- cmake/ParseWorkspace.cmake - Config parser
- Workspace-relative asset/timeline/music paths

Migration:
- Main demo: demo.seq to workspaces/main/timeline.seq
- Test demo: test_demo.seq to workspaces/test/timeline.seq
- Common shaders: assets/common/shaders
- Workspace shaders: workspaces/*/shaders

Build:
cmake -B build -DDEMO_WORKSPACE=main
cmake -B build_test -DDEMO_WORKSPACE=test

All tests passing (36/36).

handoff(Claude): Task #77 workspace system complete. Both main and test workspaces build and pass all tests.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/workspaces/test/shaders/gaussian_blur.wgsl b/workspaces/test/shaders/gaussian_blur.wgsl
new file mode 100644
index 0000000..02156f7
--- /dev/null
+++ b/workspaces/test/shaders/gaussian_blur.wgsl
@@ -0,0 +1,36 @@
+@group(0) @binding(0) var smplr: sampler;
+@group(0) @binding(1) var txt: texture_2d<f32>;
+
+#include "common_uniforms"
+struct GaussianBlurParams {
+    strength: f32,
+    _pad: f32,
+};
+
+@group(0) @binding(2) var<uniform> uniforms: CommonUniforms;
+@group(0) @binding(3) var<uniform> params: GaussianBlurParams;
+
+@vertex fn vs_main(@builtin(vertex_index) i: u32) -> @builtin(position) vec4<f32> {
+    var pos = array<vec2<f32>, 3>(
+        vec2<f32>(-1, -1),
+        vec2<f32>(3, -1),
+        vec2<f32>(-1, 3)
+    );
+    return vec4<f32>(pos[i], 0.0, 1.0);
+}
+
+@fragment fn fs_main(@builtin(position) p: vec4<f32>) -> @location(0) vec4<f32> {
+    let uv = p.xy / uniforms.resolution;
+    var res = vec4<f32>(0.0);
+
+    // Parameterized strength + dramatic beat pulsation
+    let pulse = 0.5 + uniforms.audio_intensity * 2.0;  // Pulsate between 0.5x and 2.5x with beat
+    let size = params.strength * pulse;
+
+    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 + vec2<f32>(x, y) * size / uniforms.resolution.x);
+        }
+    }
+    return res / 25.0;
+}