docs: Fix EFFECT keyword syntax and add automation-friendly workflow

Fix EFFECT keyword format across all documentation and scripts - priority
modifier (+/=/–) is required but was missing from examples.

**Documentation fixes:**
- doc/HOWTO.md: Added missing + to EFFECT example
- doc/RECIPE.md: Added priority modifiers to examples
- tools/shadertoy/README.md: Fixed test path, clarified workflow
- tools/shadertoy/convert_shadertoy.py: Updated output instructions

**New automation guide:**
- doc/EFFECT_WORKFLOW.md: Complete step-by-step checklist for AI agents
  - Exact file paths and line numbers
  - Common issues and fixes
  - Asset ID naming conventions
  - CMakeLists.txt dual-section requirement
  - Test list instructions (post_process_effects vs scene_effects)

**Integration:**
- CLAUDE.md: Added EFFECT_WORKFLOW.md to Tier 2 (always loaded)
- doc/AI_RULES.md: Added "Adding Visual Effects" quick reference
- README.md: Added EFFECT_WORKFLOW.md to documentation list

**CMakeLists.txt:**
- Disabled incomplete cube_sphere_effect.cc (ShaderToy conversion WIP)

**Timeline:**
- Commented out incomplete CubeSphereEffect
- Removed obsolete constructor argument

Fixes #issue-with-effect-syntax

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

1 files changed, 10 insertions, 6 deletions

diff --git a/tools/shadertoy/convert_shadertoy.py b/tools/shadertoy/convert_shadertoy.py
index 4956cfd..29eca1d 100755
--- a/tools/shadertoy/convert_shadertoy.py
+++ b/tools/shadertoy/convert_shadertoy.py
@@ -383,7 +383,7 @@ def main():
 
     print("✓ Files generated")
     print()
-    print("Next steps:")
+    print("Next steps (see doc/EFFECT_WORKFLOW.md for details):")
     print()
     print("1. Add shader to workspaces/main/assets.txt:")
     print(f"   shaders/{snake_name}.wgsl")
@@ -392,13 +392,17 @@ def main():
     print(f'   #include "gpu/effects/{snake_name}_effect.h"')
     print()
     print("3. Add to timeline in workspaces/main/timeline.seq:")
-    print(f"   EFFECT {effect_name}Effect 0.0 10.0 0")
+    print(f"   EFFECT + {effect_name}Effect 0.0 10.0")
     print()
-    print("4. Update tests/test_demo_effects.cc:")
-    print(f'   - Add "{effect_name}Effect" to test list')
-    print("   - Increment EXPECTED_*_COUNT")
+    print("4. Add to CMakeLists.txt GPU_SOURCES (both headless and normal mode):")
+    print(f"   src/gpu/effects/{snake_name}_effect.cc")
     print()
-    print("5. Build and test:")
+    print("5. Update src/tests/gpu/test_demo_effects.cc:")
+    print(f'   - Add "{{{effect_name}Effect", std::make_shared<{effect_name}Effect>(fixture.ctx())}}" to appropriate list')
+    print("   - Use post_process_effects (lines 80-93) for post-process effects")
+    print("   - Use scene_effects (lines 125-137) for scene effects")
+    print()
+    print("6. Build and test:")
     print("   cmake --build build -j4")
     print("   ./build/demo64k")
     print()