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/skills/optional/productivity/productivity-shop-app.md

@@ -21,7 +21,7 @@ Shop.app: product search, order tracking, returns, reorder.
 | License | MIT |
 | Platforms | linux, macos, windows |
 | Tags | `Shopping`, `E-commerce`, `Shop.app`, `Products`, `Orders`, `Returns` |
-| Related skills | [`shopify`](/docs/user-guide/skills/optional/productivity/productivity-shopify), [`maps`](/docs/user-guide/skills/bundled/productivity/productivity-maps) |
+| Related skills | [`shopify`](/user-guide/skills/optional/productivity/productivity-shopify), [`maps`](/user-guide/skills/bundled/productivity/productivity-maps) |
 
 ## Reference: full SKILL.md
 

website/docs/user-guide/skills/optional/productivity/productivity-shopify.md

@@ -21,7 +21,7 @@ Shopify Admin & Storefront GraphQL APIs via curl. Products, orders, customers, i
 | License | MIT |
 | Platforms | linux, macos, windows |
 | Tags | `Shopify`, `E-commerce`, `Commerce`, `API`, `GraphQL` |
-| Related skills | [`airtable`](/docs/user-guide/skills/bundled/productivity/productivity-airtable), [`xurl`](/docs/user-guide/skills/bundled/social-media/social-media-xurl) |
+| Related skills | [`airtable`](/user-guide/skills/bundled/productivity/productivity-airtable), [`xurl`](/user-guide/skills/bundled/social-media/social-media-xurl) |
 
 ## Reference: full SKILL.md
 

website/docs/user-guide/skills/optional/productivity/productivity-siyuan.md

@@ -21,7 +21,7 @@ SiYuan Note API for searching, reading, creating, and managing blocks and docume
 | License | MIT |
 | Platforms | linux, macos, windows |
 | Tags | `SiYuan`, `Notes`, `Knowledge Base`, `PKM`, `API` |
-| Related skills | [`obsidian`](/docs/user-guide/skills/bundled/note-taking/note-taking-obsidian), [`notion`](/docs/user-guide/skills/bundled/productivity/productivity-notion) |
+| Related skills | [`obsidian`](/user-guide/skills/bundled/note-taking/note-taking-obsidian), [`notion`](/user-guide/skills/bundled/productivity/productivity-notion) |
 
 ## Reference: full SKILL.md
 

website/docs/user-guide/skills/optional/productivity/productivity-telephony.md

@@ -21,7 +21,7 @@ Give Hermes phone capabilities without core tool changes. Provision and persist
 | License | MIT |
 | Platforms | linux, macos, windows |
 | Tags | `telephony`, `phone`, `sms`, `mms`, `voice`, `twilio`, `bland.ai`, `vapi`, `calling`, `texting` |
-| Related skills | [`maps`](/docs/user-guide/skills/bundled/productivity/productivity-maps), [`google-workspace`](/docs/user-guide/skills/bundled/productivity/productivity-google-workspace), [`agentmail`](/docs/user-guide/skills/optional/email/email-agentmail) |
+| Related skills | [`maps`](/user-guide/skills/bundled/productivity/productivity-maps), [`google-workspace`](/user-guide/skills/bundled/productivity/productivity-google-workspace), [`agentmail`](/user-guide/skills/optional/email/email-agentmail) |
 
 ## Reference: full SKILL.md