fix(omo-senpi): sweep orphaned reflection worktrees at reconciliation

Reconciliation walked run directories only, so leftovers whose run directory
was already gone were never reclaimed and accumulated on every host that lost
a reflection child.

A pass now ends with `sweepReflectionRunOrphans`, which treats the
reservation's active and pending runs plus every non-terminal run directory as
live and hands the rest to `sweepReflectionOrphans` with a 15-minute grace. A
pass that deferred on scheduler contention never sweeps, each discarded
leftover warns once through the injected logger, and a sweep failure warns
instead of failing the repair pass.

Part of #8304