TY JOUR TI Omnichannel model in FMCG: unit-economics of transition from offline to online KW omnichannel model KW fast moving consumer goods KW unit economy KW micro-hubs KW dark stores KW last mile KW pickup KW time windows KW substitution rules KW contribution margin JO JOURNAL OF MONETARY ECONOMICS AND MANAGEMENT AU Korol', M.I. PY 2025 IS 0 PB ITBO University