Mark DataGrid layout work deferred

docs/GOVERNANCE_MODEL.md

@@ -213,6 +213,10 @@ Admin lists use bounded container grids:
 
 ## Deferred Work
 
+- DataGrid sizing and resize behavior remains explicitly deferred. The current
+  bounded-grid contract above is binding, but further layout changes should be
+  handled as a dedicated, isolated UI debt item because the component is shared
+  and brittle.
 - real SMTP/IMAP test-bed verification and operator runbook;
 - recipient import with column mapping;
 - session/device revocation UI;