Remove glue submodule: models moved to shared/

The glue layer's models (MenuNode, ContainerRelation), services
(navigation, relationships), and event handlers have been absorbed
into shared/. The glue submodule caused duplicate SQLAlchemy table
registration for 'menu_nodes'.

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

.gitmodules

@@ -2,6 +2,3 @@
 	path = shared
 	url = https://git.rose-ash.com/coop/shared.git
 	branch = decoupling
-[submodule "glue"]
-	path = glue
-	url = /root/rose-ash/glue