refactor(gpu): Add RAII wrapper for WGPU resources to eliminate manual cleanup

Introduces WGPUResource template with automatic release on destruction.
Reduces boilerplate in effect destructors and prevents resource leaks.

- set() for one-time initialization
- replace() for per-frame recreation
- Field ordering documented for dependency management

Converted 3 effects (Heptagon, Flash, Passthrough) and Effect base class.
All tests pass (34/34).

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

1 files changed, 45 insertions, 0 deletions

diff --git a/src/gpu/wgpu_resource.h b/src/gpu/wgpu_resource.h
new file mode 100644
index 0000000..e448b18
--- /dev/null
+++ b/src/gpu/wgpu_resource.h
@@ -0,0 +1,45 @@
+// WGPU Resource RAII Wrapper
+// Automatic release on destruction
+//
+// IMPORTANT: Field ordering matters for destruction order.
+// Members are destroyed in reverse declaration order.
+// Declare dependencies before dependents:
+//   RenderPipeline pipeline_;  // Destroyed last
+//   BindGroup bind_group_;     // Destroyed first (may reference pipeline)
+
+#pragma once
+#include "platform/platform.h"
+#include "util/fatal_error.h"
+
+template<typename T, void(*Release)(T)>
+class WGPUResource {
+ public:
+  WGPUResource() : ptr_(nullptr) {}
+  ~WGPUResource() { if (ptr_) Release(ptr_); }
+
+  void set(T ptr) {
+    FATAL_ASSERT(ptr_ == nullptr);
+    ptr_ = ptr;
+  }
+
+  void replace(T ptr) {
+    if (ptr_) Release(ptr_);
+    ptr_ = ptr;
+  }
+
+  T get() const { return ptr_; }
+  T* get_address() { return &ptr_; }
+
+ private:
+  T ptr_;
+  WGPUResource(const WGPUResource&) = delete;
+  WGPUResource& operator=(const WGPUResource&) = delete;
+};
+
+using BindGroup = WGPUResource<WGPUBindGroup, wgpuBindGroupRelease>;
+using RenderPipeline = WGPUResource<WGPURenderPipeline, wgpuRenderPipelineRelease>;
+using ComputePipeline = WGPUResource<WGPUComputePipeline, wgpuComputePipelineRelease>;
+using Sampler = WGPUResource<WGPUSampler, wgpuSamplerRelease>;
+using Texture = WGPUResource<WGPUTexture, wgpuTextureRelease>;
+using TextureView = WGPUResource<WGPUTextureView, wgpuTextureViewRelease>;
+using Buffer = WGPUResource<WGPUBuffer, wgpuBufferRelease>;