Release importance scored 1–5; updates feed adds timeline rail

Added

• Release importance scoring (1–5) — all newly ingested releases receive an AI-scored significance rating; a flame glyph marks high-impact (4) and landmark (5) releases on feed cards and detail pages; GET /v1/releases/latest gains a ?minImportance= filter; MCP get_latest_releases and whats_changed expose a matching parameter.
• /updates redesigned with a timeline rail and composition glyphs — month rows and area chips (CLI / Web) filter the feed client-side; per-release meta lines render composition counts as filled, half, and dash glyphs; Follow, Digest, and Atom links appear in the page header.
• Category and collection scoping for search — GET /v1/search now accepts ?category=<slug> and ?collection=<slug> to narrow results to a taxonomy category or a curated collection's member orgs.
• Wider catalog and collection layouts with an export rail — /catalog and /collections expand to a wider shell; the collections index uses a two-column grid; collection detail pages gain a sticky rail with Export (.json / .md / .atom) and a Report a problem button.

Changed

• Digest emails and collection daily summaries now bias toward higher-importance releases — within each org section in digests and when selecting releases for collection date tiles, items with a higher importance score surface first.

Fixed

• Digest emails now capture releases ingested after the check window opened — editorial posts published hours before being fetched were previously dropped permanently; the email subject is also now dated for the window it covers rather than the delivery day.
• Inline code spans no longer stripped in compact org overview cards — tool names and verdict values that rendered as stray punctuation now appear correctly.