* fix(memory): make overflow errors instruct in-turn consolidation + retry
When bounded memory is full, the add/replace overflow errors now explicitly
tell the model to consolidate (merge/remove/shorten) and retry the write in
the same turn, matching the documented behavior. The replace-overflow path
now also echoes current_entries + usage for parity with add-overflow, so the
model has the same context to act on.
Closes#23378 (working-as-documented; this sharpens runtime to match docs).
* fix(memory): broaden overflow remediation hint beyond 'stale'
Say 'stale or less important' — entries don't have to be stale to be the
right ones to drop when making room.
86c537d209