Remove duplicate isomorphic-dompurify dependencies from root package.json

[BillyOutlast]

Source

PR #191 review threads:

• duplicate deps
• duplicate deps

Problem

isomorphic-dompurify and @types/dompurify are declared in both root package.json and server/package.json. In a PNPM workspace monorepo, workspace-specific deps should live in the workspace package, not the root.

Fix

Remove isomorphic-dompurify from root package.json dependencies and @types/dompurify from root package.json devDependencies. They already exist in server/package.json.

Relates: #191