refactor: Bundle GPU context into GpuContext struct

- Created GpuContext struct {device, queue, format}
- Updated Effect/PostProcessEffect to take const GpuContext&
- Updated all 19 effect implementations
- Updated MainSequence.init() and LoadTimeline() signatures
- Updated generated timeline files
- Updated all test files
- Added gpu_get_context() accessor and fixture.ctx() helper

Fixes test_mesh.cc compilation error from g_device/g_queue/g_format conflicts.
All targets build successfully.

1 files changed, 7 insertions, 6 deletions

diff --git a/src/test_demo.cc b/src/test_demo.cc
index 9ae0e3a..69b18cc 100644
--- a/src/test_demo.cc
+++ b/src/test_demo.cc
@@ -15,14 +15,14 @@
 
 // External declarations from generated files
 extern float GetDemoDuration();
-extern void LoadTimeline(MainSequence& main_seq, WGPUDevice device, WGPUQueue queue, WGPUTextureFormat format);
+extern void LoadTimeline(MainSequence& main_seq, const GpuContext& ctx);
 
 // Inline peak meter effect for debugging audio-visual sync
 #include "gpu/effects/post_process_helper.h"
 class PeakMeterEffect : public PostProcessEffect {
  public:
-  PeakMeterEffect(WGPUDevice device, WGPUQueue queue, WGPUTextureFormat format)
-      : PostProcessEffect(device, queue) {
+  PeakMeterEffect(const GpuContext& ctx)
+      : PostProcessEffect(ctx) {
     const char* shader_code = R"(
       struct VertexOutput {
         @builtin(position) position: vec4<f32>,
@@ -82,9 +82,9 @@ class PeakMeterEffect : public PostProcessEffect {
       }
     )";
 
-    pipeline_ = create_post_process_pipeline(device, format, shader_code);
+    pipeline_ = create_post_process_pipeline(device_, format_, shader_code);
     uniforms_ = gpu_create_buffer(
-        device, 16, WGPUBufferUsage_Uniform | WGPUBufferUsage_CopyDst);
+        device_, 16, WGPUBufferUsage_Uniform | WGPUBufferUsage_CopyDst);
   }
 
   void update_bind_group(WGPUTextureView input_view) {
@@ -196,7 +196,8 @@ int main(int argc, char** argv) {
 
   // Add peak meter visualization effect (renders as final post-process)
 #if !defined(STRIP_ALL)
-  auto* peak_meter = new PeakMeterEffect(g_device, g_queue, g_format);
+  const GpuContext* gpu_ctx = gpu_get_context();
+  auto* peak_meter = new PeakMeterEffect(*gpu_ctx);
   gpu_add_custom_effect(peak_meter, 0.0f, 99999.0f, 999); // High priority = renders last
 #endif