feat(articles): long-form text expression — compose, publish, read

[catomean]

The north star: OrangeCat as the best place to express thoughts via text

An article is a long-form POST on timeline_events (metadata.is_article), not a new ENTITY_REGISTRY entity. One row, free feed distribution, ~¼ the code of a new entity — reuses the createEventWithVisibility pipeline verbatim (no migration, no RPC change; metadata carries slug / cover / reading-time / markdown body).

What's in it

• config/articles.ts — SSOT (limits, slug + reading-time helpers, copy)
• services/articles/* — publishArticle (client) + getArticleBySlug / listPublishedArticles (server)
• /articles — index of published articles
• /articles/[slug] — x.ai/Substack-grade reader: design-tokens only, byline→profile, cover, reading time, OG + JSON-LD; private/followers gated to author
• /articles/new — focused composer with live Write/Preview, visibility, cover
• PostContent.tsx — feed posts flagged is_article render a "Read article" card → reader
• routes.ts — ARTICLES / ARTICLES_NEW / ARTICLE(slug)

Deliberate calls

• Markdown safety: reader uses react-markdown + rehype-sanitize + remark-gfm, not next-mdx-remote — MDX parses arbitrary user < as JSX (unsafe/fragile for user content). react-markdown never executes JSX and sanitizes HTML.
• No migration: the feed RPC only persists metadata verbatim (it derives content from description and can't set event_subtype), so the article payload rides in metadata. A slug→indexed column can be promoted later via expand/contract if volume warrants.

Verification

• type-check + lint clean; production build green (routes: /articles ƒ, /articles/[slug] ƒ, /articles/new ○); 777 unit tests pass; SSR + graceful empty-state smoke.
• Authed publish + community-feed appearance to be verified post-deploy via UI (project convention for DB-touching changes).

🤖 Generated with Claude Code