Add compound Color and Vector animation targets (pos, fill_color), closes #218

UIFrame, UICaption, and UISprite now accept "pos" as an alias for "position"
in the animation property system. UICaption and UISprite gain Vector2f
setProperty/getProperty overrides enabling animate("pos", (x, y), duration).
Color compound animation (fill_color, outline_color) was already supported.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/compound_animation_test.py

@@ -0,0 +1,82 @@
+"""Test compound (Color and Vector) animation targets - issue #218"""
+import mcrfpy
+import sys
+
+PASS = True
+
+def check(name, condition):
+    global PASS
+    if not condition:
+        print(f"FAIL: {name}")
+        PASS = False
+    else:
+        print(f"  ok: {name}")
+
+# Create a scene with test objects
+scene = mcrfpy.Scene("test_compound_anim")
+ui = scene.children
+
+frame = mcrfpy.Frame(pos=(10, 20), size=(100, 100),
+                     fill_color=mcrfpy.Color(255, 0, 0))
+ui.append(frame)
+
+cap = mcrfpy.Caption(text="hello", pos=(50, 60))
+ui.append(cap)
+
+tex = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16)
+sprite = mcrfpy.Sprite(pos=(70, 80), texture=tex)
+ui.append(sprite)
+
+mcrfpy.current_scene = scene
+
+# Test 1: Frame "pos" animation property recognized
+check("Frame hasProperty 'pos'", True)  # would fail at animate() if not
+frame.animate("pos", (200, 300), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 2: Frame "position" animation property still works
+frame2 = mcrfpy.Frame(pos=(0, 0), size=(50, 50))
+ui.append(frame2)
+frame2.animate("position", (100, 100), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 3: Frame "fill_color" compound animation
+frame.animate("fill_color", (0, 255, 0, 255), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 4: Frame "outline_color" compound animation
+frame.animate("outline_color", (128, 128, 128), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 5: Caption "pos" animation
+cap.animate("pos", (200, 200), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 6: Caption "position" animation
+cap.animate("position", (300, 300), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 7: Caption "fill_color" compound animation
+cap.animate("fill_color", (0, 0, 255), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 8: Sprite "pos" animation
+sprite.animate("pos", (200, 200), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 9: Sprite "position" animation
+sprite.animate("position", (300, 300), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 10: Frame "size" compound animation
+frame.animate("size", (200, 200), 0.5, mcrfpy.Easing.LINEAR)
+
+# Test 11: Step time forward and verify position changed
+initial_x = frame.x
+for _ in range(10):
+    mcrfpy.step(0.06)
+
+check("Frame moved from pos animation", frame.x != initial_x)
+
+# Test 12: Verify Caption position changed
+check("Caption pos changed", cap.x != 50)
+
+# Test 13: Verify Sprite position changed
+check("Sprite pos changed", sprite.x != 70)
+
+if PASS:
+    print("PASS")
+    sys.exit(0)
+else:
+    sys.exit(1)