test(memory): add owner isolation coverage for memory search

[catalini82]

I noticed the testing plan calls out owner isolation for memory search as an uncovered area.

I’d like to add a small pytest that verifies memory search does not return entries belonging to a different owner_id. The PR would be tests-only, target dev, and avoid source changes unless the test exposes an existing regression.

Would this be a welcome contribution?

[catalini82]

I can take this and prepare a small tests-only PR against dev.

[catalini82]

Opened PR: https://github.com/pewdiepie-archdaemon/odysseus/pull/3102