Fix security vulnerabilities on node-forge CVE-2025-66031 CVE-2025-12816 (#954)

* Fix security vulnerabilities

- Updated Docusaurus packages from ^3.8.1 to ^3.9.2 to fix webpack-dev-server vulnerabilities
  - @docusaurus/core
  - @docusaurus/plugin-google-tag-manager
  - @docusaurus/preset-classic
  - @docusaurus/theme-common
  - @docusaurus/module-type-aliases

- Fixed HIGH severity vulnerabilities:
  - glob: Command injection vulnerability (GHSA-5j98-mcp5-4vw2)
  - node-forge: ASN.1 vulnerabilities (GHSA-554w-wvp2-vw27, GHSA-65ch-62r8-g69g, GHSA-5gfm-wpxj-wjgq)

- Fixed MODERATE severity vulnerabilities:
  - webpack-dev-server: Source code exposure vulnerabilities (GHSA-9jgg-88mc-972h, GHSA-4v9v-hfq4-rm2v)
  - js-yaml: Prototype pollution vulnerability (GHSA-mh29-5h37-fv8m)

- Fixed LOW severity vulnerabilities:
  - brace-expansion: Regular Expression Denial of Service (GHSA-v6h2-p8h4-qcjw)
  - on-headers: HTTP response header manipulation (GHSA-76c9-3jph-rj3q)

All vulnerabilities resolved - npm audit now reports 0 vulnerabilities.

* Fix duplicate Prebid sidebar translation key

Added unique 'key' attributes to both Prebid categories to resolve duplicate translation key conflict in Japanese locale:
- Prebid category under Web: key 'Prebid-Web-Only-Guides'
- Prebid category standalone: key 'Prebid-Web-And-Mobile-Guides'

This fixes the build error: 'Multiple docs sidebar items produce the same translation key'

* removed sidebar.js change

* diff labels for Prebid web and mobile

* reverted labels changes but added back the keys

* reverted labels changes but added back the keys

Author: sunnywu