Publisher Feed Server
====================

Endpoints:
  GET /feed/{publisher_id}   - Download publisher feed (requires API key)
  GET /status                - Server status and feed activity

Authentication:
  Query param: ?api_key=YOUR_API_KEY
  Header: Authorization: Bearer YOUR_API_KEY
  Header: X-API-Key: YOUR_API_KEY

Conditional Requests:
  If-Modified-Since header supported for caching
  ETag header provided for validation