Blume changelogs auto-detected; collection digests surface

Added

• Blume changelogs — sites built on the Blume self-hosted Astro changelog generator are now auto-detected and ingested via their native RSS feed.
• AI-scored importance now reaches collection and category timelines, the following feed, live stream, search results, related rails, and MCP search results; a hover card on the flame glyph explains the 4 vs. 5 score.
• Collection weekly digests available as Markdown, JSON, and Atom — .md, .json, and .atom format adapters on the digest index; individual week pages support .md and .json.
• Recent digests surface in the collection right rail with a browse-all link; digest pages now include an AI-generated content disclaimer.

Fixed

• Collection digest pages polished — headings render at the correct depth, a covered-orgs facepile shows which companies are featured, breadcrumbs link back to the digest archive, and prev/next cards navigate between weeks.
• Geist Pixel wordmark now uses the variable font at true weight 400 — the faux-bold smear from stacked bold utilities is gone.