refactor: Modularize CMake build system into 10 specialized modules

Refactor monolithic 866-line CMakeLists.txt into 54-line orchestrator + 10 modules:
- DemoOptions.cmake - Build option declarations
- DemoConfig.cmake - Option implications and platform detection
- DemoCommon.cmake - Shared macros (conditional sources, size opts, linking)
- DemoDependencies.cmake - External library discovery (WGPU, GLFW)
- DemoSourceLists.cmake - Conditional source file lists
- DemoLibraries.cmake - Subsystem library targets
- DemoTools.cmake - Build tools (asset_packer, compilers)
- DemoCodegen.cmake - Code generation (assets, timeline, music)
- DemoExecutables.cmake - Main binaries (demo64k, test_demo)
- DemoTests.cmake - Test infrastructure (36 tests)
- Validation.cmake - Uniform buffer validation

Benefits:
- 94% reduction in main file size (866 → 54 lines)
- Conditional module inclusion (tests only parsed if DEMO_BUILD_TESTS=ON)
- Shared macros eliminate 200+ lines of repetition
- Clear separation of concerns

All 36 tests passing. All build modes verified.

Documentation: Created doc/CMAKE_MODULES.md with module architecture.

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

1 files changed, 40 insertions, 0 deletions

diff --git a/cmake/Validation.cmake b/cmake/Validation.cmake
new file mode 100644
index 0000000..fb5e71d
--- /dev/null
+++ b/cmake/Validation.cmake
@@ -0,0 +1,40 @@
+# Uniform Buffer Validation
+# Extracted from main CMakeLists.txt
+
+# Sub-task 7: Integrate validation tool into CI/build system
+
+# Ensure the Python validation script is available
+add_custom_target(validate_uniforms_script ALL DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/tools/validate_uniforms.py)
+
+# Find all WGSL files recursively in src/gpu
+file(GLOB WGSL_FILES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/*.wgsl ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/**/*.wgsl)
+
+# List of C++ files containing uniform struct definitions and shader code
+# Add more C++ files here if new effects with structs are added.
+set(VALIDATION_CPP_FILES
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/heptagon_effect.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/post_process_helper.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/fade_effect.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/theme_modulation_effect.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/chroma_aberration_effect.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/vignette_effect.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/gaussian_blur_effect.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/distort_effect.cc
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/demo_effects.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/gpu/effects/circle_mask_effect.h
+)
+
+# Add custom command to run the validator
+# It depends on the script itself, WGSL files, and the C++ files being validated.
+# Outputting a flag file to signal completion.
+set(VALIDATION_FLAG ${CMAKE_CURRENT_BINARY_DIR}/uniform_validation_complete.flag)
+add_custom_command(
+    OUTPUT ${VALIDATION_FLAG}
+    COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_SOURCE_DIR}/tools/validate_uniforms.py ${VALIDATION_FLAG}
+    COMMAND python3 ${CMAKE_CURRENT_SOURCE_DIR}/tools/validate_uniforms.py ${CMAKE_CURRENT_SOURCE_DIR}/assets/final/shaders ${VALIDATION_CPP_FILES}
+    DEPENDS validate_uniforms_script ${WGSL_FILES} ${VALIDATION_CPP_FILES}
+    COMMENT "Validating uniform buffer sizes and alignments..."
+)
+
+# Add custom target that depends on the validation output flag
+add_custom_target(validate_uniforms ALL DEPENDS ${VALIDATION_FLAG})