Add pop/find/extend to EntityCollection3D, closes #243

EntityCollection3D now has API parity with UIEntityCollection:
- pop(index=-1): Remove and return entity at index
- find(name): Search by entity name, return Entity3D or None
- extend(iterable): Append multiple Entity3D objects

Also adds `name` property to Entity3D for use with find().

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/test_entity_collection3d_methods.py

@@ -0,0 +1,97 @@
+"""Test EntityCollection3D pop/find/extend (issue #243)"""
+import mcrfpy
+import sys
+
+errors = []
+
+vp = mcrfpy.Viewport3D(pos=(0,0), size=(100,100))
+vp.set_grid_size(16, 16)
+
+# Setup: add 5 named entities
+for i in range(5):
+    e = mcrfpy.Entity3D(pos=(i, i), scale=1.0)
+    e.name = f"entity_{i}"
+    vp.entities.append(e)
+
+# Test find - existing
+found = vp.entities.find("entity_2")
+if found is None:
+    errors.append("find('entity_2') returned None")
+elif found.name != "entity_2":
+    errors.append(f"find returned wrong entity: {found.name}")
+
+# Test find - missing
+missing = vp.entities.find("nonexistent")
+if missing is not None:
+    errors.append("find('nonexistent') should return None")
+
+# Test pop() - default (last element)
+count_before = len(vp.entities)
+popped = vp.entities.pop()
+if popped.name != "entity_4":
+    errors.append(f"pop() should return last, got {popped.name}")
+if len(vp.entities) != count_before - 1:
+    errors.append(f"Length should decrease after pop")
+
+# Test pop(0) - first element
+popped0 = vp.entities.pop(0)
+if popped0.name != "entity_0":
+    errors.append(f"pop(0) should return first, got {popped0.name}")
+
+# Test pop(1) - middle element
+popped1 = vp.entities.pop(1)
+if popped1.name != "entity_2":
+    errors.append(f"pop(1) should return index 1, got {popped1.name}")
+
+# Current state: [entity_1, entity_3]
+if len(vp.entities) != 2:
+    errors.append(f"Expected 2 remaining, got {len(vp.entities)}")
+
+# Test pop - out of range
+try:
+    vp.entities.pop(99)
+    errors.append("pop(99) should raise IndexError")
+except IndexError:
+    pass
+
+# Test extend
+new_entities = []
+for i in range(3):
+    e = mcrfpy.Entity3D(pos=(10+i, 10+i), scale=1.0)
+    e.name = f"new_{i}"
+    new_entities.append(e)
+vp.entities.extend(new_entities)
+if len(vp.entities) != 5:
+    errors.append(f"After extend, expected 5, got {len(vp.entities)}")
+
+# Verify extended entities are findable
+if vp.entities.find("new_1") is None:
+    errors.append("Extended entity not findable")
+
+# Test extend with invalid type
+try:
+    vp.entities.extend([42])
+    errors.append("extend with non-Entity3D should raise TypeError")
+except TypeError:
+    pass
+
+# Test extend with non-iterable
+try:
+    vp.entities.extend(42)
+    errors.append("extend with non-iterable should raise TypeError")
+except TypeError:
+    pass
+
+# Test name property
+e_named = mcrfpy.Entity3D(pos=(0,0), scale=1.0)
+e_named.name = "test_name"
+if e_named.name != "test_name":
+    errors.append(f"name property: expected 'test_name', got '{e_named.name}'")
+
+if errors:
+    for err in errors:
+        print(f"FAIL: {err}", file=sys.stderr)
+    sys.exit(1)
+else:
+    print("PASS: EntityCollection3D pop/find/extend (issue #243)", file=sys.stderr)
+    sys.exit(0)