feat(backend): replace backend with peter branch + Emergency Care integration

fix(applications): replace MySQL-only FIELD() and CONCAT() with SQLite-compatible equivalents

fix: sync all API changes to new schema — review notes, care campaigns, investment guard

feat(membership): integrate membership module into mdn-backend-main + HF Docker deployment

feat(calendly): shared Calendly API client + real advisory-meeting booking on Applications

feat(membership): admin-driven account creation, real estate tier/investment work, in-progress monorepo migration state