Complete M11 Creator Studio and M12 Trust & Safety for PC5

- Creator Studio: Visual behavior & property inspector, GLB model importer, binary persistence
- Trust & Safety: 18+ TOS confirmation (DOB removed), creator guidelines & briefing card on join, in-game reporting HUD
- Test Harness: Add --filter, --skip-backend, --skip-godot to run_checkpoint_tests.py

scripts/editor/object_catalog.gd

@@ -64,5 +64,20 @@ func get_all_ids() -> Array[String]:
 	return ids
 
 
+func register_custom_object(id: String, entry: Dictionary) -> bool:
+	if not _loaded:
+		_catalog = {}
+		_loaded = true
+	_catalog[id] = entry
+	return true
+
+
+func remove_custom_object(id: String) -> bool:
+	if not _loaded:
+		return false
+	return _catalog.erase(id)
+
+
 func get_catalog_path() -> String:
 	return _catalog_path
+