- Create separate RssParser and AtomParser implementing IParser interface
- Add utility functions for ID generation (djb2 hash) and date parsing
- Support both RSS (RFC 822) and Atom (ISO 8601) date formats
- Handle Atom elements with attributes (type="html") via #text property
- Map RSS <description> to summary and <content:encoded> to content
- Map Atom <summary> to summary and <content> to content
- Prefer Atom link[@rel="alternate"] for article URLs
- Throw descriptive errors for malformed XML and missing required fields
- Add comprehensive test coverage for both parsers (32 tests total)
