fix: Update packages and fix local dev (#26907)

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- [x] I have read [freeCodeCamp's contribution guidelines](https://github.com/freeCodeCamp/freeCodeCamp/blob/master/CONTRIBUTING.md).
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client/gatsby-config.js

@@ -2,6 +2,14 @@ const path = require('path');
 
 const { buildChallenges } = require('./utils/buildChallenges');
 
+const { NODE_ENV: env, LOCALE: locale = 'english' } = process.env;
+
+const selectedGuideDir = `../${
+  env === 'production' ? 'guide' : 'mock-guide'
+}/${locale}`;
+const guideRoot = path.resolve(__dirname, selectedGuideDir);
+const curriculumIntroRoot = path.resolve(__dirname, './src/pages');
+
 module.exports = {
   siteMetadata: {
     title: 'freeCodeCamp',
@@ -32,10 +40,17 @@ module.exports = {
       }
     },
     {
-      resolve: '@freecodecamp/gatsby-source-filesystem',
+      resolve: 'gatsby-source-filesystem',
+      options: {
+        name: 'guides',
+        path: guideRoot
+      }
+    },
+    {
+      resolve: 'gatsby-source-filesystem',
       options: {
         name: 'introductions',
-        path: path.resolve(__dirname, './src/pages')
+        path: curriculumIntroRoot
       }
     },
     {
@@ -110,7 +125,7 @@ module.exports = {
         }
       }
     },
-    'fcc-create-nav-data',
+    { resolve: 'fcc-create-nav-data' },
     {
       resolve: 'gatsby-plugin-manifest',
       options: {