Cold outreach sequencer

Build a cold email outreach tool.

Core features:
1. Import prospects (CSV) with fields like name, company, role
2. Create a sequence: 3-5 steps with delays and merge tags
3. Connect Gmail via OAuth to send from user's inbox
4. Track opens, replies (stop on reply), unsubscribes
5. Dashboard: reply rate per sequence

Data: prospects, sequences, steps, sends, events.
Must-haves: rate-limited sending, threading (reply to previous), unsubscribe footer.