Integrates origin/huey/system-manager-design1715efb78(base6c75887b0) as one doc-only commit: docs/plans/2026-10-21_q198-system-manager.md (blob4fbebd3e, pinned code evidence base6c75887b0) plus Huey's 14 BUILD-LOG lines and 7 SESSIONS lines, appended unchanged. Scrooge approved r6 (scrooge-0004) and confirmed r6.1 N1-N3 closed (scrooge-0005). No package, script, runtime or queue change. Slices S1-S6 go to the queue under Vikunja 452.