Implement comprehensive animation system (closes #59)

- Add Animation class with 30+ easing functions (linear, ease in/out, quad, cubic, elastic, bounce, etc.)
- Add property system to all UI classes for animation support:
  - UIFrame: position, size, colors (including individual r/g/b/a components)
  - UICaption: position, size, text, colors
  - UISprite: position, scale, sprite_number (with sequence support)
  - UIGrid: position, size, camera center, zoom
  - UIEntity: position, sprite properties
- Create AnimationManager singleton for frame-based updates
- Add Python bindings through PyAnimation wrapper
- Support for delta animations (relative values)
- Fix segfault when running scripts directly (mcrf_module initialization)
- Fix headless/windowed mode behavior to respect --headless flag
- Animations run purely in C++ without Python callbacks per frame

All UI properties are now animatable with smooth interpolation and professional easing curves.

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

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

src/UIFrame.h

@@ -42,6 +42,15 @@ public:
     static PyGetSetDef getsetters[];
     static PyObject* repr(PyUIFrameObject* self);
     static int init(PyUIFrameObject* self, PyObject* args, PyObject* kwds);
+    
+    // Animation property system
+    bool setProperty(const std::string& name, float value) override;
+    bool setProperty(const std::string& name, const sf::Color& value) override;
+    bool setProperty(const std::string& name, const sf::Vector2f& value) override;
+    
+    bool getProperty(const std::string& name, float& value) const override;
+    bool getProperty(const std::string& name, sf::Color& value) const override;
+    bool getProperty(const std::string& name, sf::Vector2f& value) const override;
 };
 
 namespace mcrfpydef {