Add ensureGridstate() helper that unconditionally checks gridstate size
against current grid dimensions and resizes if mismatched. Replace all
lazy-init guards (size == 0) with ensureGridstate() calls.
Previously, gridstate was only initialized when empty. When an entity
moved to a differently-sized grid, gridstate kept the old size, causing
heap buffer overflows when updateVisibility() or at() iterated using the
new grid's dimensions.
Also adds spatial_hash.remove() calls in set_grid() before removing
entities from old grids, and replaces PyObject_GetAttrString type lookup
with direct &mcrfpydef::PyUIGridType reference.
Closes#258, closes#259, closes#260, closes#261, closes#262,
closes#263, closes#274, closes#276, closes#278
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
John McCardle
348826a0f5