{Website} Upgrade docusaurus-plugin-internaldocs-fb to unblock lodash-es security fix

Summary:
GitHub Dependabot cannot create a security PR to upgrade lodash-es from 4.17.23 to 4.18.1 because the transitive dependency chain pins it to an exact version:

docusaurus-plugin-internaldocs-fb@1.19.2 → chevrotain@11.1.1 → lodash-es "4.17.23" (exact, no caret)

This diff upgrades docusaurus-plugin-internaldocs-fb from ^1.19.1 to ^1.19.3, which replaces the chevrotain dependency with mermaid (uses lodash-es "^4.17.23", allowing 4.18.1). It also adds a yarn resolution for langium >= 4.2.2, because langium 4.2.1 still pulls in chevrotain 11.1.1; langium 4.2.2 switches to chevrotain 12.0.0, which dropped lodash-es entirely.

After this change, no chevrotain 11.x remains in yarn.lock, and all lodash-es references use ^ semver ranges compatible with 4.18.1.

Differential Revision: D102057545

Author: kongchen1992

website/package.json

@@ -30,7 +30,7 @@
     "@mdx-js/react": "^3.1.0",
     "@types/react": "^18.3.3",
     "clsx": "^2.1.1",
-    "docusaurus-plugin-internaldocs-fb": "^1.19.1",
+    "docusaurus-plugin-internaldocs-fb": "^1.19.3",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-loadable": "^5.5.0",
@@ -76,6 +76,7 @@
   },
   "resolutions": {
     "cheerio": "1.0.0-rc.12",
-    "@mdx-js/react": "^3.1.0"
+    "@mdx-js/react": "^3.1.0",
+    "langium": "^4.2.2"
   }
 }