One constructor replaces four hand-rolled Pane literals (router x2,
tests x2) and owns argv-derived titles. set_lifecycle now takes the
transition time, records lifecycle_since, and stores the length of the
last working stretch in last_run_secs. Both fields are optional so old
snapshots still load.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>