refactor: Simplify effect render API and fix uniform initialization

Root cause: Uniform buffers created but not initialized before bind group
creation, causing undefined UV coordinates in circle_mask_compute.wgsl.

Changes:
- Add get_common_uniforms() helper to Effect base class
- Refactor render()/compute() signatures: 5 params → CommonPostProcessUniforms&
- Fix uninitialized uniforms in CircleMaskEffect and CNNEffect
- Update all 19 effect implementations and headers
- Fix WGSL syntax error in FlashEffect (u.audio_intensity → audio_intensity)
- Update test files (test_sequence.cc)

Benefits:
- Cleaner API: construct uniforms once per frame, reuse across effects
- More maintainable: CommonPostProcessUniforms changes need no call site updates
- Fixes UV coordinate bug in circle_mask_compute.wgsl

All 36 tests passing (100%)

handoff(Claude): Effect API refactor complete

1 files changed, 22 insertions, 22 deletions

diff --git a/src/gpu/demo_effects.h b/src/gpu/demo_effects.h
index 1ccf930..8cdf557 100644
--- a/src/gpu/demo_effects.h
+++ b/src/gpu/demo_effects.h
@@ -33,8 +33,8 @@ struct Particle {
 class HeptagonEffect : public Effect {
  public:
   HeptagonEffect(const GpuContext& ctx);
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
 
  private:
   RenderPass pass_;
@@ -43,10 +43,10 @@ class HeptagonEffect : public Effect {
 class ParticlesEffect : public Effect {
  public:
   ParticlesEffect(const GpuContext& ctx);
-  void compute(WGPUCommandEncoder encoder, float time, float beat,
-               float intensity, float aspect_ratio) override;
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void compute(WGPUCommandEncoder encoder,
+               const CommonPostProcessUniforms& uniforms) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
 
  private:
   ComputePass compute_pass_;
@@ -65,8 +65,8 @@ class PassthroughEffect : public PostProcessEffect {
 class MovingEllipseEffect : public Effect {
  public:
   MovingEllipseEffect(const GpuContext& ctx);
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
 
  private:
   RenderPass pass_;
@@ -75,10 +75,10 @@ class MovingEllipseEffect : public Effect {
 class ParticleSprayEffect : public Effect {
  public:
   ParticleSprayEffect(const GpuContext& ctx);
-  void compute(WGPUCommandEncoder encoder, float time, float beat,
-               float intensity, float aspect_ratio) override;
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void compute(WGPUCommandEncoder encoder,
+               const CommonPostProcessUniforms& uniforms) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
 
  private:
   ComputePass compute_pass_;
@@ -100,8 +100,8 @@ class GaussianBlurEffect : public PostProcessEffect {
   GaussianBlurEffect(const GpuContext& ctx);
   // New parameterized constructor
   GaussianBlurEffect(const GpuContext& ctx, const GaussianBlurParams& params);
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
   void update_bind_group(WGPUTextureView input_view) override;
 
  private:
@@ -112,8 +112,8 @@ class GaussianBlurEffect : public PostProcessEffect {
 class SolarizeEffect : public PostProcessEffect {
  public:
   SolarizeEffect(const GpuContext& ctx);
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
   void update_bind_group(WGPUTextureView input_view) override;
 
  private:
@@ -129,8 +129,8 @@ class VignetteEffect : public PostProcessEffect {
  public:
   VignetteEffect(const GpuContext& ctx);
   VignetteEffect(const GpuContext& ctx, const VignetteParams& params);
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
   void update_bind_group(WGPUTextureView input_view) override;
 
  private:
@@ -151,8 +151,8 @@ class ChromaAberrationEffect : public PostProcessEffect {
   // New parameterized constructor
   ChromaAberrationEffect(const GpuContext& ctx,
                          const ChromaAberrationParams& params);
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
   void update_bind_group(WGPUTextureView input_view) override;
 
  private:
@@ -171,8 +171,8 @@ class DistortEffect : public PostProcessEffect {
  public:
   DistortEffect(const GpuContext& ctx);
   DistortEffect(const GpuContext& ctx, const DistortParams& params);
-  void render(WGPURenderPassEncoder pass, float time, float beat,
-              float intensity, float aspect_ratio) override;
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
   void update_bind_group(WGPUTextureView input_view) override;
 
  private: