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/messaging/index.md

@@ -8,7 +8,7 @@ description: "Chat with Hermes from Telegram, Discord, Slack, WhatsApp, Signal,
 
 Chat with Hermes from Telegram, Discord, Slack, WhatsApp, Signal, SMS, Email, Home Assistant, Mattermost, Matrix, DingTalk, Feishu/Lark, WeCom, Weixin, BlueBubbles (iMessage), QQ, Yuanbao, Microsoft Teams, LINE, ntfy, or your browser. The gateway is a single background process that connects to all your configured platforms, handles sessions, runs cron jobs, and delivers voice messages.
 
-For the full voice feature set — including CLI microphone mode, spoken replies in messaging, and Discord voice-channel conversations — see [Voice Mode](/docs/user-guide/features/voice-mode) and [Use Voice Mode with Hermes](/docs/guides/use-voice-mode-with-hermes).
+For the full voice feature set — including CLI microphone mode, spoken replies in messaging, and Discord voice-channel conversations — see [Voice Mode](/user-guide/features/voice-mode) and [Use Voice Mode with Hermes](/guides/use-voice-mode-with-hermes).
 
 ## Platform Comparison
 
@@ -257,7 +257,7 @@ gateway:
 
 #### Inspecting your access
 
-Use `/whoami` from any platform to see the active scope, your tier (admin / user / unrestricted), and which slash commands you can run. See the [Telegram](/docs/user-guide/messaging/telegram#slash-command-access-control) and [Discord](/docs/user-guide/messaging/discord#slash-command-access-control) pages for platform-specific examples.
+Use `/whoami` from any platform to see the active scope, your tier (admin / user / unrestricted), and which slash commands you can run. See the [Telegram](/user-guide/messaging/telegram#slash-command-access-control) and [Discord](/user-guide/messaging/discord#slash-command-access-control) pages for platform-specific examples.
 
 ## Interrupting the Agent