docs: translation module (#14271)

* docs: translation module

* fix link in JS SDK

* add translations user guides [WIP]

* updates

* fix broken link

* remove mentions of default locale

* change header

* updates

* updated user guides

* handle todos

* fix build error

* fix lint errors

www/apps/book/generated/edit-dates.mjs

@@ -135,7 +135,7 @@ export const generatedEditDates = {
   "app/learn/fundamentals/workflows/locks/page.mdx": "2025-12-09T11:20:25.011Z",
   "app/learn/codemods/page.mdx": "2025-09-29T15:40:03.620Z",
   "app/learn/codemods/replace-imports/page.mdx": "2025-10-09T11:37:44.754Z",
-  "app/learn/fundamentals/admin/translations/page.mdx": "2025-10-30T11:55:32.221Z",
+  "app/learn/fundamentals/admin/translations/page.mdx": "2025-12-16T13:56:21.400Z",
   "app/learn/configurations/medusa-config/asymmetric-encryption/page.mdx": "2025-10-31T09:53:38.607Z",
   "app/learn/best-practices/third-party-sync/page.mdx": "2025-12-03T11:48:58.209Z"
 }