generate_articles() was storing url_path with lang prefix (/en/markets/...)
but the content blueprint is registered at /<lang>, producing double-prefix
URLs like /en/en/markets/italy. Fix: store url_path without prefix, build
full_url with prefix for SEO tags (canonical, OG, hreflang, breadcrumbs).
Also removes /markets from RESERVED_PREFIXES since article sub-paths under
/markets/ are valid pSEO content URLs, not blueprint routes.
Subtask 1 of pSEO template improvements.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>