Add customergroup and entity HTTP APIs with address and contact routes.

Expose store-backed CRUD for customer groups, entities, nested addresses, and contacts, matching the documented dashdbschema contracts.

src/db/store.js

@@ -21,6 +21,10 @@ const STORE_NAMESPACES = [
     'posterminal',
     'supplier',
     'delivery',
+    'customergroup',
+    'entity',
+    'entityaddress',
+    'entitycontact',
 ];
 
 /**