test(server): windowed snapshots must not wait on the SQLite writer

Failing regression test for #21840. getThreadSnapshotWindow runs in a
writer transaction, so a held writer makes the snapshot fail with
"database is locked" instead of reading the committed thread.

Test taken unchanged from #21869 by ScottN-PV.

Co-Authored-By: ScottN-PV <191782757+ScottN-PV@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
9f597f2058Julius Marminge committed on 10/22/2026, 10:14:16 AMparent8d3b061
1 file changedLine totals unavailable