v1.0.384

fix(chat): count the archive from the server, not the cached index

The history heading read its chat count off the context's thread index, which
is a snapshot from this tab's last hydration. A thread added since — by another
tab, or written straight to the server — appeared in the list below while the
heading still quoted the old number, so the two disagreed on screen.

Take the count from an unfiltered search response instead, and decrement it on
delete so it tracks without a refetch.

Claude-Session: https://claude.ai/code/session_01FbNUfdN67fEjpg7WdgQpLD