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/unit/test_empty_animation_manager.py

@@ -1,20 +1,28 @@
 #!/usr/bin/env python3
 """
 Test if AnimationManager crashes with no animations
+Refactored to use mcrfpy.step() for synchronous execution.
 """
 
 import mcrfpy
+import sys
 
 print("Creating empty scene...")
 test = mcrfpy.Scene("test")
 test.activate()
 
 print("Scene created, no animations added")
-print("Starting game loop in 100ms...")
+print("Advancing simulation with step()...")
 
-def check_alive(timer, runtime):
-    print(f"Timer fired at {runtime}ms - AnimationManager survived!")
-    mcrfpy.Timer("exit", lambda t, r: mcrfpy.exit(), 100, once=True)
+# Step multiple times to simulate game loop running
+# If AnimationManager crashes with empty state, this will fail
+try:
+    for i in range(10):
+        mcrfpy.step(0.1)  # 10 steps of 0.1s = 1 second simulated
 
-mcrfpy.Timer("check", check_alive, 1000, once=True)
-print("If this crashes immediately, AnimationManager has an issue with empty state")
+    print("AnimationManager survived 10 steps with no animations!")
+    print("PASS")
+    sys.exit(0)
+except Exception as e:
+    print(f"FAIL: AnimationManager crashed: {e}")
+    sys.exit(1)