feat(website): /features index + multilingual sitemap (hreflang + lastmod + sitemap-index + robots.txt)

[montfort]

Summary

SEO improvement so crawlers (Google + friends) understand the site's information tree (features / docs / blog) and how each section's content branches into the three shipped locales (en / es / zh-CN).

The trigger: the sitemap analysis from the previous turn showed three gaps — no `/features` aggregator page (asymmetric with `/blog` and `/docs`), no hreflang annotations relating the per-locale URLs, and no `robots.txt` to make the three per-locale sitemaps discoverable from a single entry point.

What changed

1. `/features` index page (consistency with /blog and /docs)

• `website/src/pages/features/{index.tsx, index.module.css}` — new aggregator page that renders `FeatureGrid` wrapped in a small header (eyebrow + H1 + intro). The nine `/features/` pages now have a parent index, matching the pattern `/blog` and `/docs` already had.
• `website/src/components/FeaturesLayout/index.tsx` gains a sidebar "Overview" link back to the new `/features` index, with active-state detection that doesn't false-match on `/features/`.
• i18n — six new keys per locale (`features.index.eyebrow`, `features.index.title`, `features.index.intro`, `features.sidebar.overview`, `meta.features.title`, `meta.features.description`) in `website/i18n/{es,zh-CN}/code.json`.

2. Sitemap plugin: hreflang + lastmod

• `docusaurus.config.ts` preset.classic.sitemap — new `createSitemapItems` that wraps the default emitter and adds `xhtml:link rel="alternate" hreflang="..."` per URL for all three locales + `x-default`. Google uses these to cluster per-locale URLs as translations (not duplicates).
• `lastmod: 'date'` + `showLastUpdateTime: true` on the docs and blog plugins + `future.experimental_vcs: 'git-eager'` so the sitemap plugin can read git history per file efficiently.

3. Static SEO files

• `website/static/sitemap-index.xml` — aggregates the three per-locale sitemaps (`/sitemap.xml`, `/es/sitemap.xml`, `/zh-CN/sitemap.xml`) so crawlers discover all locales from one entry point.
• `website/static/robots.txt` — declares `Sitemap: https://straymark.dev/sitemap-index.xml\`. Without this, the multi-sitemap setup is not auto-discoverable (Google would only crawl the canonical `/sitemap.xml` and miss `/es` + `/zh-CN` unless submitted manually to Search Console).

Local build verification

After `npm run build`:

Sitemap	URLs	hreflang links	lastmod	Notes
`build/sitemap.xml`	80	320	23	EN canonical
`build/es/sitemap.xml`	80	320	16	ES
`build/zh-CN/sitemap.xml`	80	320	16	zh-CN

• 80 URLs per locale (was 79; +1 for the new `/features` index).
• 320 hreflang annotations per sitemap = 80 URLs × 4 alternates (en + es + zh-CN + x-default). 960 total across the three sitemaps.
• lastmod populated on all content pages (docs + blog). Aggregator pages (`/blog`, `/blog/tags/*`, `/blog/archive`, etc.) correctly have no lastmod — they don't map to a single source file.
• `build/{sitemap-index.xml, robots.txt}` present at root.
• `/features` renders correctly in all three locales: title, H1, and eyebrow translated.

Sample `` entry (the new `/features`):

```xml

https://straymark.dev/features
weekly
0.5
<xhtml:link rel="alternate" hreflang="en" href="https://straymark.dev/features"/>
<xhtml:link rel="alternate" hreflang="es" href="https://straymark.dev/es/features"/>
<xhtml:link rel="alternate" hreflang="zh-CN" href="https://straymark.dev/zh-CN/features"/>
<xhtml:link rel="alternate" hreflang="x-default" href="https://straymark.dev/features"/>

```

Test plan

• `npm run typecheck` clean
• `npm run build` clean for all three locales
• Sitemap output verified locally (counts above)
• `/features` index renders with translated metadata in en/es/zh-CN
• After merge + deploy: verify `curl -sI https://straymark.dev/{robots.txt, sitemap-index.xml, features}` all return 200
• After merge + deploy: submit `sitemap-index.xml` to Search Console (optional accelerator; robots.txt makes it crawl-discoverable automatically over time)

Known limitations (acceptable for v1)

• lastmod on static pages (`src/pages/*`: `/features`, `/quickstart`, `/privacy`, `/`) is not populated. The pages plugin doesn't propagate `metadata.lastUpdatedAt`. Low SEO impact (Google ignores lastmod when not trusted; pages change rarely anyway). Can be added in a follow-up if needed.
• lastmod on translated docs is partial — the docs plugin reads from the synced location (`website/i18n/{locale}/.../current/`) which is gitignored, so git lookup returns no timestamp. Fixing this would require either modifying `scripts/sync-docs-i18n.ts` to preserve the canonical source's git timestamp on the synced file, or pointing the sitemap to the canonical source. Out of scope for this PR.

🤖 Generated with Claude Code