I'm Interested API

Collect email interest for your offers.

NOTE: Use an obscure offer name if you don't want others to find it.
      The offer name is the only thing protecting your list.

ENDPOINTS
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POST /api/interests
  Body: { "email": "...", "offerName": "...", "description": "..." }
  Creates offer if it doesn't exist, adds email to interest list.
  Description is optional, only used when creating a new offer.
  Duplicate emails are ignored.

GET /api/interests/:offerName
  Returns: { "description": "...", "emails": [{ "email": "...", "createdAt": "..." }] }
  Returns 404 if offer doesn't exist.

GET /api/health
  Returns: { "status": "ok", "timestamp": "..." }