[WC-3540]: chore(html-element-web): bump dompurify to 3.4.13

[r0b1n]

Summary

• Bumped dompurify from 3.4.12 to 3.4.13 in html-element-web
• Updated pnpm-lock.yaml (only dompurify changed)
• Added changelog entry under [Unreleased]

Test plan

• Verify widget builds successfully
• Confirm no regressions in HTML sanitization behavior

[github-actions]

AI Code Review

✅ Approved — no issues found

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What was reviewed

File	Change
packages/pluggableWidgets/html-element-web/CHANGELOG.md	Added ### Security entry under [Unreleased] for dompurify bump
packages/pluggableWidgets/html-element-web/package.json	Bumped dompurify dependency from ^3.4.12 → ^3.4.13

Skipped (out of scope): pnpm-lock.yaml

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Positives

• Changelog entry is correctly categorized under ### Security (Keep a Changelog format) — matches the nature of the change.
• Changelog message is user-facing and benefit-oriented ("incorporate latest security fixes"), not an implementation detail.
• Lockfile updated in the same PR, ensuring deterministic builds.
• Change is tightly scoped to only the affected package — no collateral edits.