feat: Phase 1 - safe constructors and _Drawable foundation

Closes #7 - Make all UI class constructors safe:
- Added safe default constructors for UISprite, UIGrid, UIEntity, UICaption
- Initialize all members to predictable values
- Made Python init functions accept no arguments
- Added x,y properties to UIEntity

Closes #71 - Create _Drawable Python base class:
- Created PyDrawable.h/cpp with base type (not yet inherited by UI types)
- Registered in module initialization

Closes #87 - Add visible property:
- Added bool visible=true to UIDrawable base class
- All render methods check visibility before drawing

Closes #88 - Add opacity property:
- Added float opacity=1.0 to UIDrawable base class
- UICaption and UISprite apply opacity to alpha channel

Closes #89 - Add get_bounds() method:
- Virtual method returns sf::FloatRect(x,y,w,h)
- Implemented in Frame, Caption, Sprite, Grid

Closes #98 - Add move() and resize() methods:
- move(dx,dy) for relative movement
- resize(w,h) for absolute sizing
- Caption resize is no-op (size controlled by font)

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

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

src/UIGrid.cpp

@@ -3,7 +3,27 @@
 #include "McRFPy_API.h"
 #include <algorithm>
 
-UIGrid::UIGrid() {}
+UIGrid::UIGrid() 
+: grid_x(0), grid_y(0), zoom(1.0f), center_x(0.0f), center_y(0.0f), ptex(nullptr)
+{
+    // Initialize entities list
+    entities = std::make_shared<std::list<std::shared_ptr<UIEntity>>>();
+    
+    // Initialize box with safe defaults
+    box.setSize(sf::Vector2f(0, 0));
+    box.setPosition(sf::Vector2f(0, 0));
+    box.setFillColor(sf::Color(0, 0, 0, 0));
+    
+    // Initialize render texture (small default size)
+    renderTexture.create(1, 1);
+    
+    // Initialize output sprite
+    output.setTextureRect(sf::IntRect(0, 0, 0, 0));
+    output.setPosition(0, 0);
+    output.setTexture(renderTexture.getTexture());
+    
+    // Points vector starts empty (grid_x * grid_y = 0)
+}
 
 UIGrid::UIGrid(int gx, int gy, std::shared_ptr<PyTexture> _ptex, sf::Vector2f _xy, sf::Vector2f _wh)
 : grid_x(gx), grid_y(gy),
@@ -44,6 +64,11 @@ void UIGrid::update() {}
 
 void UIGrid::render(sf::Vector2f offset, sf::RenderTarget& target)
 {
+    // Check visibility
+    if (!visible) return;
+    
+    // TODO: Apply opacity to output sprite
+    
     output.setPosition(box.getPosition() + offset); // output sprite can move; update position when drawing
     // output size can change; update size when drawing
     output.setTextureRect(
@@ -202,6 +227,29 @@ PyObjectsEnum UIGrid::derived_type()
     return PyObjectsEnum::UIGRID;
 }
 
+// Phase 1 implementations
+sf::FloatRect UIGrid::get_bounds() const
+{
+    auto pos = box.getPosition();
+    auto size = box.getSize();
+    return sf::FloatRect(pos.x, pos.y, size.x, size.y);
+}
+
+void UIGrid::move(float dx, float dy)
+{
+    box.move(dx, dy);
+}
+
+void UIGrid::resize(float w, float h)
+{
+    box.setSize(sf::Vector2f(w, h));
+    // Recreate render texture with new size
+    if (w > 0 && h > 0) {
+        renderTexture.create(static_cast<unsigned int>(w), static_cast<unsigned int>(h));
+        output.setTexture(renderTexture.getTexture());
+    }
+}
+
 std::shared_ptr<PyTexture> UIGrid::getTexture()
 {
     return ptex;
@@ -218,14 +266,14 @@ UIDrawable* UIGrid::click_at(sf::Vector2f point)
 
 
 int UIGrid::init(PyUIGridObject* self, PyObject* args, PyObject* kwds) {
-    int grid_x, grid_y;
+    int grid_x = 0, grid_y = 0;  // Default to 0x0 grid
     PyObject* textureObj = Py_None;
     //float box_x, box_y, box_w, box_h;
     PyObject* pos = NULL;
     PyObject* size = NULL;
 
     //if (!PyArg_ParseTuple(args, "iiOffff", &grid_x, &grid_y, &textureObj, &box_x, &box_y, &box_w, &box_h)) {
-    if (!PyArg_ParseTuple(args, "ii|OOO", &grid_x, &grid_y, &textureObj, &pos, &size)) {
+    if (!PyArg_ParseTuple(args, "|iiOOO", &grid_x, &grid_y, &textureObj, &pos, &size)) {
         return -1; // If parsing fails, return an error
     }