docs: flesh §12 Sustainability economics & health metrics; backlog → §13
Promote §12 backlog item #2 into a full section (parametric unit-economics
break-even, "non-profit ≠ needn't cover costs" vs §7/§11 UBIT, North Star =
% GMV cross-maker-referred + leading indicators tied to §9 gates and the §7
order-history asset, volunteer-sustainability reliability-floor economics).
Renumber backlog §12 → §13 (remove promoted item, renumber remainder),
fix cross-refs (§7, §9, §10), OHM-grounded per top-of-file note.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
ben.stull
452acc97b0