Keep a Planner workflow live until its lifecycle says it ended

Chopin counted a workflow root as live only while Atomic reported it
working or blocked. Atomic also reports a live run as idle and quiescent
whenever nothing is counted as executing, for example between steps, so
Chopin released the Planner session mid-run, dropped its card, and left
the run orphaned. A root is now paused when Atomic says so, ended only
once its run's lifecycle reports an end or the root disappears, and live
otherwise.

Assistant-model: Claude Opus 5.5
Assistant-workflow: inline
Assistant-verification: bun test passed: 1757 pass, 2 PostgreSQL skips, 0 fail, including a quiescent root of a live run counted as live
Assistant-verification: bun run types passed: all workspaces
Assistant-verification: bun run ci passed: dprint, oxlint, tokens, type scale, Impeccable (no new findings)
Assistant-verification: agent-browser E2E failed before this change: on Atomic 0.9.25-alpha.5 the run card vanished eight minutes into grill-me-1 and the run made no further progress
Co-authored-by: Alex Lavaee <lavaman131@github.com>