fix: prevent 2-letter folder names from being misidentified as locale codes

getPagePath() used a regex to extract locale prefixes from file paths, but
any top-level folder with a 2-letter name (e.g. AI/, CI/) or 2+2-letter
hyphenated name (e.g. CI-CD/) matched the BCP 47 locale pattern, causing
the extracted non-existent locale to violate the pages_localecode_foreign
FK constraint on insert.

Now validates the extracted locale against the configured locales
(WIKI.config.lang.code + WIKI.config.lang.namespaces) before accepting it.

Cherry-picked from requarks/wiki requarks#7958

Author: syphernl

server/helpers/page.js

@@ -143,9 +143,16 @@ module.exports = {
     }
     const result = localeFolderRegex.exec(meta.path)
     if (result[1]) {
-      meta = {
-        locale: result[1].replace('/', ''),
-        path: result[2]
+      const extractedLocale = result[1].replace('/', '')
+      const knownLocales = new Set([
+        WIKI.config.lang.code,
+        ...(WIKI.config.lang.namespaces || [])
+      ])
+      if (knownLocales.has(extractedLocale)) {
+        meta = {
+          locale: extractedLocale,
+          path: result[2]
+        }
       }
     }
     return meta