Remove unnecessary npm overrides for prismjs and dompurify (#225)

Summary:
Dependencies now use secure versions natively. The `prismjs` and `dompurify` overrides were added previously to fix security vulnerabilities, but upstream packages have since updated their dependencies to use patched versions.

## Changes

- Remove `overrides` section from `package.json`
- Update `package-lock.json` to reflect native dependency resolution

Pull Request resolved: #225

Test Plan:
- Verified `npm ls prismjs` shows 1.30.0 (patched version)
- Verified `npm ls dompurify` shows 3.3.0 (> 3.2.4, patched version)

Reviewed By: wychi

Differential Revision: D89703525

Pulled By: FindHao

fbshipit-source-id: 65a0594cf2d0061ad5bafdea6ea66a9896743d01

Author: FindHao

website/package-lock.json

@@ -38,9 +38,5 @@
     "typescript": "^5.9.3",
     "typescript-eslint": "^8.50.1",
     "vite": "^7.3.0"
-  },
-  "overrides": {
-    "prismjs": "^1.30.0",
-    "dompurify": "^3.2.4"
   }
 }