test(acp): pin the two Claude title producers to one normalization

claude-agent-acp 0.73.0 publishes its generated title over the wire and
persists it to the session file, so for the first time both the ACP
notification and the transcript reader feed `publish_native_title` on a
Claude connection. Its skip-cache only collapses identical strings, and two
producers admitting different ones can broadcast out of order, so a
divergence between the wire trim/cap and `capture_title_record`'s would turn
every long title into a permanent two-writer ping-pong on the sidebar row.

The two already agree; this asserts one against the other so a future change
to either cap has to change both.