fix(schema): add direction outbound for self-referencing relationship

InterfaceEthernet.connected_interface is a self-reference that requires
direction: outbound to avoid bidirectional conflicts per Infrahub docs.

Ref: #41

schemas/base.yml

@@ -213,6 +213,8 @@ nodes:
         description: Parent LAG interface
       - name: connected_interface
         peer: InfraInterfaceEthernet
+        identifier: ethernet_connected_to
+        direction: outbound
         cardinality: one
         optional: true
         description: Connected peer interface