Python API improvements: Vectors, bounds, window singleton, hidden types

- #177: GridPoint.grid_pos property returns (x, y) tuple
- #179: Grid.grid_size returns Vector instead of tuple
- #181: Grid.center returns Vector instead of tuple
- #182: Caption.size/w/h read-only properties for text dimensions
- #184: mcrfpy.window singleton for window access
- #185: Removed get_bounds() method, use .bounds property instead
- #188: bounds/global_bounds return (pos, size) as pair of Vectors
- #189: Hide internal types from module namespace (iterators, collections)

Also fixed critical bug: Changed static PyTypeObject to inline in headers
to ensure single instance across translation units (was causing segfaults).

Closes #177, closes #179, closes #181, closes #182, closes #184, closes #185, closes #188, closes #189

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

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

src/PyDrawable.cpp

@@ -123,13 +123,6 @@ static PyGetSetDef PyDrawable_getsetters[] = {
     {NULL}  // Sentinel
 };
 
-// get_bounds method implementation (#89)
-static PyObject* PyDrawable_get_bounds(PyDrawableObject* self, PyObject* Py_UNUSED(args))
-{
-    auto bounds = self->data->get_bounds();
-    return Py_BuildValue("(ffff)", bounds.left, bounds.top, bounds.width, bounds.height);
-}
-
 // move method implementation (#98)
 static PyObject* PyDrawable_move(PyDrawableObject* self, PyObject* args, PyObject* kwds)
 {
@@ -156,13 +149,6 @@ static PyObject* PyDrawable_resize(PyDrawableObject* self, PyObject* args, PyObj
 
 // Method definitions
 static PyMethodDef PyDrawable_methods[] = {
-    {"get_bounds", (PyCFunction)PyDrawable_get_bounds, METH_NOARGS,
-     MCRF_METHOD(Drawable, get_bounds,
-         MCRF_SIG("()", "tuple"),
-         MCRF_DESC("Get the bounding rectangle of this drawable element."),
-         MCRF_RETURNS("tuple: (x, y, width, height) representing the element's bounds")
-         MCRF_NOTE("The bounds are in screen coordinates and account for current position and size.")
-     )},
     {"move", (PyCFunction)PyDrawable_move, METH_VARARGS | METH_KEYWORDS,
      MCRF_METHOD(Drawable, move,
          MCRF_SIG("(dx, dy) or (delta)", "None"),