build: fold SCA dependency updates

Created by: ihsraham

Summary

• Folds the open SCA dependency updates from Dependabot PRs #141, #142, #143, #144, and #145 into one branch based on fresh develop.
• Updates package-lock.json for fast-xml-parser, fast-xml-builder, fast-uri, uuid, dompurify, and related transitive fixes.
• Adds a package override so Next resolves to the patched root postcss version instead of retaining its vulnerable nested copy.

Validation

• npm ci
• npm audit --audit-level=moderate
• npm run build