Epic Product Engineer public discovery

Base URL: https://www.epicproduct.engineer

Start here:
- https://www.epicproduct.engineer/sitemap.md -> markdown discovery index
- https://www.epicproduct.engineer/sitemap.xml -> XML sitemap for crawlers
- https://www.epicproduct.engineer/llms.txt -> short operator hint surface
- https://www.epicproduct.engineer/rss.xml -> RSS feed for content updates

Human route families:
- Posts: `https://www.epicproduct.engineer/<slug>`
- Workshop lessons: `https://www.epicproduct.engineer/workshops/<module>/<lesson>` for free public lessons
- Workshop landing pages: `https://www.epicproduct.engineer/workshops/<module>`

Markdown twins:
- Posts: `https://www.epicproduct.engineer/<slug>.md`
- Workshop lessons: `https://www.epicproduct.engineer/workshops/<module>/<lesson>.md` for free public lessons

Formats:
- HTML by default
- Markdown via explicit .md twins on supported public content
- JSON discovery via /api
- RSS feed at /rss.xml

Notes:
- Discovery surfaces only reference public or free content.
- Accept: text/markdown content negotiation works on post and lesson routes.