feat: improve search visibility and developer discovery

[mustafazeydani]

What changed

• replaces keyword-heavy SEO surfaces with localized, useful dataset coverage, provenance, use-case, limitation, and freshness content
• adds a localized, crawlable /api developer landing page with metadata and WebAPI structured data
• fixes sitemap dates, canonical English redirects, robots directives, tracking-parameter cleanup, and 404 indexing behavior
• improves internal dataset and API discovery links
• refreshes transitive dependency overrides so the enforced audit gate has zero known advisories

Why

The public site had confirmed technical and content-quality SEO issues, while the main-domain developer API intent had no dedicated landing page. Newly published dependency advisories also blocked the production audit gate.

Validation

• pnpm verify
• production Next.js build: 47/47 pages generated
• pnpm audit: zero known vulnerabilities
• EN/AR metadata, canonical, hreflang, sitemap, robots, JSON-LD, redirects, 404s, and mobile API layout smoke-tested