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, 1 insertions, 1 deletions

diff --git a/src/gpu/effects/flash_cube_effect.h b/src/gpu/effects/flash_cube_effect.h
index 3af13eb..7089af2 100644
--- a/src/gpu/effects/flash_cube_effect.h
+++ b/src/gpu/effects/flash_cube_effect.h
@@ -11,7 +11,7 @@
 
 class FlashCubeEffect : public Effect {
  public:
-  FlashCubeEffect(WGPUDevice device, WGPUQueue queue, WGPUTextureFormat format);
+  FlashCubeEffect(const GpuContext& ctx);
   void init(MainSequence* demo) override;
   void resize(int width, int height) override;
   void render(WGPURenderPassEncoder pass, float time, float beat,