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, 53 insertions, 0 deletions

diff --git a/workspaces/test/shaders/solarize.wgsl b/workspaces/test/shaders/solarize.wgsl
new file mode 100644
index 0000000..de15dfc
--- /dev/null
+++ b/workspaces/test/shaders/solarize.wgsl
@@ -0,0 +1,53 @@
+@group(0) @binding(0) var smplr: sampler;
+@group(0) @binding(1) var txt: texture_2d<f32>;
+
+#include "common_uniforms"
+
+@group(0) @binding(2) var<uniform> uniforms: CommonUniforms;
+
+@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 col = textureSample(txt, smplr, uv);
+
+    // Patterns are 2 seconds long (120 BPM, 4 beats)
+    let pattern_num = u32(uniforms.time / 2.0);
+    let is_even_pattern = (pattern_num % 2u) == 0u;
+
+    // Reduced threshold range for subtler effect
+    let thr = 0.4 + 0.15 * sin(uniforms.time);
+    let solarize_strength = 0.4;  // Reduced from 1.0 for less saturation
+
+    if (is_even_pattern) {
+        // Even patterns: Subtle red-orange tint
+        if (col.r < thr) {
+            col.r = mix(col.r, 1.0 - col.r, solarize_strength);
+        }
+        if (col.g < thr) {
+            col.g = mix(col.g, 1.0 - col.g * 0.7, solarize_strength * 0.7);
+        }
+        if (col.b < thr) {
+            col.b = mix(col.b, col.b * 0.5, solarize_strength);
+        }
+    } else {
+        // Odd patterns: Subtle blue-cyan tint
+        if (col.r < thr) {
+            col.r = mix(col.r, col.r * 0.6, solarize_strength);
+        }
+        if (col.g < thr) {
+            col.g = mix(col.g, 1.0 - col.g * 0.8, solarize_strength * 0.8);
+        }
+        if (col.b < thr) {
+            col.b = mix(col.b, 1.0 - col.b, solarize_strength);
+        }
+    }
+    return col;
+}