Add lastOutputAt tracking on heartbeat runs, updated from adapter stdout/stderr
with batched DB writes (30s debounce). The orphan reaper now checks running
processes for idle timeout: warns at 10 min, kills (SIGTERM/SIGKILL) at 15 min.
- DB: add last_output_at column to heartbeat_runs (migration 0046)
- Server: idle warning/kill logic in reapOrphanedRuns, lastOutputAt flush in onLog
- Server: clear idle_warning on activity report (clearDetachedRunWarning)
- API: expose errorCode and lastOutputAt on active/recent run endpoints
- UI: orange idle warning badge on ActiveAgentsPanel and LiveRunWidget
- UI: show last output relative time in LiveRunWidget
- UI: add idle_timeout status color
Co-Authored-By: Paperclip <noreply@paperclip.ing>