docs: complete beat-based timing documentation

Updated all affected documentation files:
- UNIFORM_BUFFER_GUIDELINES.md: New CommonUniforms example
- ARCHITECTURE.md: Beat-based timing section
- EFFECT_WORKFLOW.md: Available uniforms reference
- CONTRIBUTING.md: Updated uniform buffer checklist

handoff(Claude): Beat-based timing system fully implemented and documented.

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

1 files changed, 3 insertions, 3 deletions

diff --git a/doc/CONTRIBUTING.md b/doc/CONTRIBUTING.md
index 98df873..d7ef88a 100644
--- a/doc/CONTRIBUTING.md
+++ b/doc/CONTRIBUTING.md
@@ -153,8 +153,8 @@ To ensure consistency and prevent alignment-related issues:
 2. **Mirror in C++:** Create corresponding C++ structs that mirror WGSL definitions.
 3. **`static_assert` for Size:** Every C++ struct must have a `static_assert` verifying size matches WGSL.
 4. **Standard Bindings:**
-   - **Binding 2:** Always use `CommonPostProcessUniforms` for per-frame data (resolution, time, beat).
+   - **Binding 2:** Always use `CommonPostProcessUniforms` for per-frame data (resolution, time, beat_time, beat_phase, audio_intensity).
    - **Binding 3:** Use effect-specific parameter structs for unique data.
-5. **Shader Consistency:** Ensure WGSL shaders correctly declare uniforms at specified bindings.
+5. **Shader Consistency:** Use `ShaderComposer` to include `common_uniforms` snippet. Reference `CommonUniforms` struct in WGSL shaders.
 6. **Validation Script:** Run `tools/validate_uniforms.py` to catch discrepancies.
-7. **Documentation:** Refer to `doc/UNIFORM_BUFFER_GUIDELINES.md` for detailed alignment rules.
+7. **Documentation:** Refer to `doc/UNIFORM_BUFFER_GUIDELINES.md` for detailed alignment rules and `doc/BEAT_TIMING.md` for timing usage.