Implements RSS 2.0 feed generation using feedgen library.
Features:
- generate_feed() creates standards-compliant RSS 2.0 XML
- RFC-822 date formatting for pubDate elements
- Title extraction from note content (first line or timestamp)
- CDATA safety for HTML content
- Configurable feed item limits
Follows ADR-014 RSS implementation strategy.
Related: docs/decisions/ADR-014-rss-feed-implementation.md
