refactor: complete removal of 'Effect' suffix from C++ class names

Update effect class definitions in headers and implementations to match
timeline.seq naming convention. All tests passing (34/34).

Classes renamed:
- PassthroughEffect → Passthrough
- GaussianBlurEffect → GaussianBlur
- PlaceholderEffect → Placeholder
- HeptagonEffect → Heptagon
- ParticlesEffect → Particles
- RotatingCubeEffect → RotatingCube
- Hybrid3DEffect → Hybrid3D
- FlashEffect → Flash
- PeakMeterEffect → PeakMeter

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

1 files changed, 2 insertions, 2 deletions

diff --git a/src/effects/placeholder_effect.cc b/src/effects/placeholder_effect.cc
index d8852da..6127e0c 100644
--- a/src/effects/placeholder_effect.cc
+++ b/src/effects/placeholder_effect.cc
@@ -6,7 +6,7 @@
 #include "gpu/shaders.h"
 #include <cstdio>
 
-PlaceholderEffect::PlaceholderEffect(const GpuContext& ctx,
+Placeholder::Placeholder(const GpuContext& ctx,
                                          const std::vector<std::string>& inputs,
                                          const std::vector<std::string>& outputs,
                                          const char* placeholder_name)
@@ -33,7 +33,7 @@ PlaceholderEffect::PlaceholderEffect(const GpuContext& ctx,
   sampler_ = wgpuDeviceCreateSampler(ctx_.device, &sampler_desc);
 }
 
-void PlaceholderEffect::render(WGPUCommandEncoder encoder,
+void Placeholder::render(WGPUCommandEncoder encoder,
                                  const UniformsSequenceParams& params,
                                  NodeRegistry& nodes) {
   WGPUTextureView input_view = nodes.get_view(input_nodes_[0]);