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/UIEntity.cpp

@@ -386,6 +386,7 @@ PyGetSetDef UIEntity::getsetters[] = {
     {"y", (getter)UIEntity::get_float_member, (setter)UIEntity::set_float_member, "Entity y position", (void*)1},
     {"visible", (getter)UIEntity_get_visible, (setter)UIEntity_set_visible, "Visibility flag", NULL},
     {"opacity", (getter)UIEntity_get_opacity, (setter)UIEntity_set_opacity, "Opacity (0.0 = transparent, 1.0 = opaque)", NULL},
+    {"name", (getter)UIEntity_get_name, (setter)UIEntity_set_name, "Name for finding elements", NULL},
     {NULL}  /* Sentinel */
 };