Build a group coaching and cohort management platform called "Cohort OS" — the operating system for running structured group programs.

Core features:
- Program builder: coach sets program name, session count, cadence (weekly/bi-weekly), max participants, price, and start date. Each session has a title, a pre-work assignment, and a post-session reflection prompt
- Participant portal: each enrolled participant sees their program timeline, upcoming sessions, submitted assignments, and peer reflections in one dashboard
- Assignment submission: participants submit written or link-based assignments before each session. Coach sees all submissions in one view, can leave written feedback per submission
- Peer feedback rounds: after each session, participants are prompted to give one piece of structured feedback to one other participant (rotates automatically so everyone gives and receives equally)
- Progress tracker: coach dashboard showing assignment completion rate per participant, attendance, and a simple engagement score
- Certificate generation: at program completion, auto-generates a PDF certificate with participant name, program name, coach name, and completion date

Stack: React, Supabase, Stripe Connect for coach payouts, Resend for session reminders and feedback prompts. Clean, professional design — coach-first UX.