#1097 fixed mempalace_search to treat empty-string wing/room as
no filter, matching how LLM agents default to filling every optional
parameter with ''. The same pattern wasn't applied to diary_read:
passing wing='' defaulted to wing_<agent_name>, siloing away entries
that hooks had written to project-derived wings per #659.
When wing is empty/omitted, filter only on agent + room=diary so
callers get a unified view of the agent's journal across every wing
it has written to. Explicit wing=<name> continues to scope reads
to that wing only.
Adds test covering empty-wing read after writing to both the default
and a non-default wing.
Igor Lins e Silva
1fd16daac2