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, 4 insertions, 5 deletions

diff --git a/src/gpu/effects/flash_effect.cc b/src/gpu/effects/flash_effect.cc
index 176c60c..3dcb48a 100644
--- a/src/gpu/effects/flash_effect.cc
+++ b/src/gpu/effects/flash_effect.cc
@@ -5,9 +5,8 @@
 #include "gpu/effects/post_process_helper.h"
 #include <cmath>
 
-FlashEffect::FlashEffect(WGPUDevice device, WGPUQueue queue,
-                         WGPUTextureFormat format)
-    : PostProcessEffect(device, queue) {
+FlashEffect::FlashEffect(const GpuContext& ctx)
+    : PostProcessEffect(ctx) {
   const char* shader_code = R"(
     struct VertexOutput {
       @builtin(position) position: vec4<f32>,
@@ -48,9 +47,9 @@ FlashEffect::FlashEffect(WGPUDevice device, WGPUQueue queue,
     }
   )";
 
-  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 FlashEffect::update_bind_group(WGPUTextureView input_view) {