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/working_timer_test.py

@@ -11,16 +11,16 @@ mcrfpy.setScene("timer_works")
 ui = mcrfpy.sceneUI("timer_works")
 
 # Add visible content
-frame = mcrfpy.Frame(100, 100, 300, 200,
+frame = mcrfpy.Frame(pos=(100, 100), size=(300, 200),
                     fill_color=mcrfpy.Color(255, 0, 0),
                     outline_color=mcrfpy.Color(255, 255, 255),
                     outline=3.0)
 ui.append(frame)
 
-caption = mcrfpy.Caption(mcrfpy.Vector(150, 150),
+caption = mcrfpy.Caption(pos=(150, 150),
                         text="TIMER TEST SUCCESS",
                         fill_color=mcrfpy.Color(255, 255, 255))
-caption.size = 24
+caption.font_size = 24
 ui.append(caption)
 
 # Timer callback with correct signature