feat(sequence): complete phase 3 - v2 shader integration and effect ports

- Create v2-compatible WGSL shaders with UniformsSequenceParams
- Add sequence_v2_uniforms snippet for ShaderComposer
- Port 3 effects: PassthroughEffectV2, GaussianBlurEffectV2, HeptagonEffectV2
- Enable and fix end-to-end test (test_sequence_v2_e2e)
- Fix shader binding order (sampler at 0, texture at 1)
- Fix WebGPU validation (maxAnisotropy=1, explicit depthSlice)
- Add v2 shaders to main and test workspace assets
- All tests passing (36/36)

handoff(Claude): Phase 3 complete, v2 effects functional, ready for phase 4

2 files changed, 12 insertions, 0 deletions

diff --git a/workspaces/main/assets.txt b/workspaces/main/assets.txt
index 189e965..0558ae1 100644
--- a/workspaces/main/assets.txt
+++ b/workspaces/main/assets.txt
@@ -78,3 +78,9 @@ CIRCLE_MASK_COMPUTE_SHADER, NONE, shaders/circle_mask_compute.wgsl, "Circle mask
 CIRCLE_MASK_RENDER_SHADER, NONE, shaders/circle_mask_render.wgsl, "Circle mask render shader"
 MASKED_CUBE_SHADER, NONE, shaders/masked_cube.wgsl, "Masked cube shader"
 SHADER_SCENE1, NONE, shaders/scene1.wgsl, "Scene1 effect shader"
+
+# --- Sequence v2 Shaders ---
+SHADER_SEQUENCE_V2_UNIFORMS, NONE, ../../common/shaders/sequence_v2_uniforms.wgsl, "Sequence v2 Uniforms Snippet"
+SHADER_PASSTHROUGH_V2, NONE, ../../common/shaders/passthrough_v2.wgsl, "Passthrough Shader (v2)"
+SHADER_GAUSSIAN_BLUR_V2, NONE, ../../common/shaders/gaussian_blur_v2.wgsl, "Gaussian Blur Shader (v2)"
+SHADER_HEPTAGON_V2, NONE, ../../common/shaders/heptagon_v2.wgsl, "Heptagon Shader (v2)"
diff --git a/workspaces/test/assets.txt b/workspaces/test/assets.txt
index 8eb692e..5ed8af6 100644
--- a/workspaces/test/assets.txt
+++ b/workspaces/test/assets.txt
@@ -68,6 +68,12 @@ CIRCLE_MASK_COMPUTE_SHADER, NONE, shaders/circle_mask_compute.wgsl, "Circle mask
 CIRCLE_MASK_RENDER_SHADER, NONE, shaders/circle_mask_render.wgsl, "Circle mask render shader"
 MASKED_CUBE_SHADER, NONE, shaders/masked_cube.wgsl, "Masked cube shader"
 
+# --- Sequence v2 Shaders ---
+SHADER_SEQUENCE_V2_UNIFORMS, NONE, ../../common/shaders/sequence_v2_uniforms.wgsl, "Sequence v2 Uniforms Snippet"
+SHADER_PASSTHROUGH_V2, NONE, ../../common/shaders/passthrough_v2.wgsl, "Passthrough Shader (v2)"
+SHADER_GAUSSIAN_BLUR_V2, NONE, ../../common/shaders/gaussian_blur_v2.wgsl, "Gaussian Blur Shader (v2)"
+SHADER_HEPTAGON_V2, NONE, ../../common/shaders/heptagon_v2.wgsl, "Heptagon Shader (v2)"
+
 # --- Test Assets (for test_assets.cc) ---
 TEST_ASSET_1, NONE, test_assets/test_asset_1.txt, "Test static asset"
 TEST_IMAGE, NONE, test_assets/test_image.png, "Test 2x2 RGBA PNG image"