fix: Update test files to use current API patterns

Migrates test suite to current API:
- Frame(x, y, w, h) → Frame(pos=(x, y), size=(w, h))
- Caption("text", x, y) → Caption(pos=(x, y), text="text")
- caption.size → caption.font_size
- Entity(x, y, ...) → Entity((x, y), ...)
- Grid(w, h, ...) → Grid(grid_size=(w, h), ...)
- cell.color → ColorLayer system

Tests now serve as valid API usage examples.

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

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

tests/unit/test_properties_quick.py

@@ -10,7 +10,7 @@ def test_properties(runtime):
     
     # Test Frame
     try:
-        frame = mcrfpy.Frame(10, 10, 100, 100)
+        frame = mcrfpy.Frame(pos=(10, 10), size=(100, 100))
         print(f"Frame visible: {frame.visible}")
         frame.visible = False
         print(f"Frame visible after setting to False: {frame.visible}")