L11 grouping: turn it on by default only with published winning numbers #189

Lane L11. Needs the L10 run (FreeMixer/openmixer#2263). Flip grouping to on, with the group_max and group_cost_max of the winning run, and a conformance test that reads the published documents and refuses the flip without them. If the numbers lose, grouping stays off.

Design: https://github.com/FreeMixer/plugin-hostd/blob/main/docs/design/notes/2026-10-27-grouping-planner.md (PR #183). Part of #182, FreeMixer/plugin-qualify#157, FreeMixer/openmixer#2263. Operator priority 2026-10-27. One repo, one small change, with its test and the sabotage that reds it.