fix(website): cross-locale doc links + drop empty ko locale (#31895)

The locale switcher appeared broken because hardcoded markdown links
(`](/docs/X)`) got double-prefixed by Docusaurus to `/docs/<locale>/docs/X`
(404) in non-English locales, and the MDX hero `<a href>` on the index
page escaped locale routing entirely.

Changes:
- Rewrite 922 `](/docs/X)` -> `](/X)` across 166 docs files (strip trailing
  .md too). Docusaurus prepends locale + baseUrl itself.
- docs/index.md -> index.mdx; hero "Get Started" anchor -> Docusaurus
  <Link> so it stays inside the active locale.
- Drop `ko` locale entirely from docusaurus.config.ts + delete i18n/ko/
  (4 stale auto-translated kanban pages, <2% coverage, misleading).

Verified `npm run build` succeeds for both en and zh-Hans; `build/zh-Hans/
index.html` has no /docs/zh-Hans/docs/... double-prefixed paths.

PR2 will translate the 335 English docs into i18n/zh-Hans/.

website/docs/user-guide/windows-native.md

@@ -83,7 +83,7 @@ Top-to-bottom, in order:
 10. **Runs `hermes setup`** — the normal first-run wizard (model, provider, toolsets). Skip with `-SkipSetup`.
 
 :::tip Skip provider hunting on Windows
-Native Windows is still early beta, and per-tool API key setup (Firecrawl, FAL, Browser Use, OpenAI TTS) is the highest-friction part of getting a useful agent. A [Nous Portal](/docs/user-guide/features/tool-gateway) subscription covers the model **and** all of those tools through one OAuth login. After the installer finishes, run `hermes setup --portal` to wire everything up.
+Native Windows is still early beta, and per-tool API key setup (Firecrawl, FAL, Browser Use, OpenAI TTS) is the highest-friction part of getting a useful agent. A [Nous Portal](/user-guide/features/tool-gateway) subscription covers the model **and** all of those tools through one OAuth login. After the installer finishes, run `hermes setup --portal` to wire everything up.
 :::
 
 ## Feature matrix