Refactor 11 more tests to mcrfpy.step() pattern

Converted from Timer-based async to step()-based sync:
- test_simple_callback.py
- test_empty_animation_manager.py
- test_frame_clipping.py
- test_frame_clipping_advanced.py
- test_grid_children.py
- test_color_helpers.py
- test_no_arg_constructors.py
- test_properties_quick.py
- test_simple_drawable.py
- test_python_object_cache.py
- WORKING_automation_test_example.py

Only 4 tests remain with Timer-based patterns (2 are headless detection
tests that may require special handling).

🤖 Generated with Claude Code (https://claude.com/claude-code)

Co-Authored-By: Frack <frack@goblincorps.dev>
Co-Authored-By: Claude <noreply@anthropic.com>

tests/KNOWN_ISSUES.md

@@ -89,30 +89,28 @@ The following tests have been converted to use `mcrfpy.step()`:
 - test_animation_removal.py
 - test_timer_callback.py
 - test_timer_once.py
+- test_simple_callback.py
+- test_empty_animation_manager.py
+- test_frame_clipping.py
+- test_frame_clipping_advanced.py
+- test_grid_children.py
+- test_color_helpers.py
+- test_no_arg_constructors.py
+- test_properties_quick.py
+- test_simple_drawable.py
+- test_python_object_cache.py
+- WORKING_automation_test_example.py
 
 ## Remaining Timeout Failures
 
 These tests still use Timer-based async patterns:
-- WORKING_automation_test_example.py
 - benchmark_logging_test.py
 - keypress_scene_validation_test.py
-- test_empty_animation_manager.py
-- test_simple_callback.py
 
 **Headless mode tests:**
 - test_headless_detection.py
 - test_headless_modes.py
 
-**Other timing-dependent:**
-- test_color_helpers.py
-- test_frame_clipping.py
-- test_frame_clipping_advanced.py
-- test_grid_children.py
-- test_no_arg_constructors.py
-- test_properties_quick.py
-- test_python_object_cache.py
-- test_simple_drawable.py
-
 ## Running Tests
 
 ```bash