feat: implement name system for finding UI elements (#39/40/41)

- Add 'name' property to UIDrawable base class
- All UI elements (Frame, Caption, Sprite, Grid, Entity) support .name
- Entity delegates name to its sprite member
- Add find(name, scene=None) function for exact match search
- Add findAll(pattern, scene=None) with wildcard support (* matches any sequence)
- Both functions search recursively through Frame children and Grid entities
- Comprehensive test coverage for all functionality

This provides a simple way to find UI elements by name in Python scripts,
supporting both exact matches and wildcard patterns.

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

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

src/UIGrid.cpp

@@ -637,6 +637,7 @@ PyGetSetDef UIGrid::getsetters[] = {
 
     {"texture", (getter)UIGrid::get_texture, NULL, "Texture of the grid", NULL}, //TODO 7DRL-day2-item5
     {"z_index", (getter)UIDrawable::get_int, (setter)UIDrawable::set_int, "Z-order for rendering (lower values rendered first)", (void*)PyObjectsEnum::UIGRID},
+    {"name", (getter)UIDrawable::get_name, (setter)UIDrawable::set_name, "Name for finding elements", (void*)PyObjectsEnum::UIGRID},
     UIDRAWABLE_GETSETTERS,
     {NULL}  /* Sentinel */
 };