fix(docs): strengthen crawl + indexing signals for the blog

[rejifald]

Why

Google Search Console reports ~107 blog/docs URLs as "Discovered — currently not indexed."

I checked every technical cause and there's no blocker: blog posts are statically generated, robots/canonical/sitemap are clean, and there's no noindex in the HTML or response headers (proxy.ts, next.config headers(), security-headers.mjs all verified). This is the classic young-domain crawl-budget pattern — Google discovered the whole sitemap at once and is metering how fast it crawls because the domain has little authority yet.

The dominant fix is non-code (see Follow-up below), but this PR maximizes the on-site signals that help Google prioritize crawling the URLs it has already discovered — and fixes one real anti-pattern.

Changes

• Truthful sitemap <lastmod> (app/sitemap.ts) — was stamping every URL with the build timestamp, so each deploy told Google all ~107 pages changed simultaneously. Google treats an always-current lastmod as untrustworthy and ignores it, discarding the signal it uses to schedule crawls. Now each blog URL reports its real frontmatter date; the blog index uses the newest post's date. (Docs/home stay on build time — no per-page date available.)
• Per-post BlogPosting JSON-LD (app/(home)/blog/[slug]/page.tsx) — the root layout emits site-wide WebSite/SoftwareApplication, but posts had none. Adds headline, datePublished, author, image, mainEntityOfPage so crawlers model each post as an Article (aids prioritization; unlocks Article rich results).
• Per-post OG image route (app/og/blog/[slug]/route.tsx, new) — mirrors the existing docs OG route, wired into openGraph/twitter/JSON-LD. Posts previously declared a summary_large_image card with no image, so social cards rendered blank.
• "From the blog" home section (app/(home)/components/from-the-blog.tsx, new) — links the 4 latest posts from the home page. The home page is the most-crawled URL, so direct links from it are the strongest crawl-priority signal we can give the posts.

Verification

• /sitemap.xml served live returns distinct per-post <lastmod> dates (2026-07-08, 2026-07-02, 2026-06-30, 2026-06-29…) instead of one build timestamp.
• Docs typecheck passes (tsc --noEmit after next typegen) — the new typed RouteContext<'/og/blog/[slug]'> route resolves.
• Home page renders the section with 4 crawlable /blog/* links + a "Read the blog" CTA (confirmed in the served HTML and via DOM inspect).
• No existing test asserts homepage structure, sitemap contents, or JSON-LD.

Follow-up (not code — the dominant lever)

These get pages indexed faster than any code change on a young domain:

1. Request indexing for priority URLs in GSC (URL Inspection → Request Indexing; rate-limited ~10–15/day) — spend them on /blog + top posts + key docs.
2. Confirm the sitemap is submitted (GSC → Sitemaps → "Success").
3. Keep building authority/backlinks (awesome-lists, registries, writeups) — each external link Google follows raises crawl priority.
4. Patience — the "Validate Fix" started 7/3 re-runs automatically; a young domain indexes gradually over weeks.

🤖 Generated with Claude Code