Sanitize blog post HTML

[phucnguyen1707]

Summary

• sanitize stored blog HTML before rendering it with dangerouslySetInnerHTML
• keep common prose tags and safe attributes while blocking scripts, event handlers, and unsafe URL schemes
• add sanitize-html as an explicit web dependency

Fixes #15

Checks

• pnpm --filter @c0upons/web run typecheck
• pnpm --filter @c0upons/web exec eslint 'app/blog/[slug]/page.tsx' lib/sanitize-blog-html.ts
• pnpm --filter @c0upons/web run build

Note: full app lint still reports pre-existing errors outside this change in about, home, privacy, terms, offline, and api/webhooks/crawlproof.

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	@​types/​sanitize-html@​2.16.1
	sanitize-html@​2.17.5

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[socket-security]

Warning

Review the following alerts detected in dependencies.

According to your organization's Security Policy, it is recommended to resolve "Warn" alerts. Learn more about Socket for GitHub.

Action	Severity	Alert  (click "▶" to expand/collapse)
Warn		Obfuscated code: npm entities is 91.0% likely obfuscated Confidence: 0.91 Location: Package overview From: pnpm-lock.yaml → npm/@types/sanitize-html@2.16.1 → npm/sanitize-html@2.17.5 → npm/entities@4.5.0 ℹ Read more on: This package | This alert | What is obfuscated code? Next steps: Take a moment to review the security alert above. Review the linked package source code to understand the potential risk. Ensure the package is not malicious before proceeding. If you're unsure how to proceed, reach out to your security team or ask the Socket team for help at support@socket.dev. Suggestion: Packages should not obfuscate their code. Consider not using packages with obfuscated code. Mark the package as acceptable risk. To ignore this alert only in this pull request, reply with the comment @SocketSecurity ignore npm/entities@4.5.0. You can also ignore all packages with @SocketSecurity ignore-all. To ignore an alert for all future pull requests, use Socket's Dashboard to change the triage state of this alert.
Warn		Obfuscated code: npm htmlparser2 is 90.0% likely obfuscated Confidence: 0.90 Location: Package overview From: pnpm-lock.yaml → npm/@types/sanitize-html@2.16.1 → npm/sanitize-html@2.17.5 → npm/htmlparser2@10.1.0 ℹ Read more on: This package | This alert | What is obfuscated code? Next steps: Take a moment to review the security alert above. Review the linked package source code to understand the potential risk. Ensure the package is not malicious before proceeding. If you're unsure how to proceed, reach out to your security team or ask the Socket team for help at support@socket.dev. Suggestion: Packages should not obfuscate their code. Consider not using packages with obfuscated code. Mark the package as acceptable risk. To ignore this alert only in this pull request, reply with the comment @SocketSecurity ignore npm/htmlparser2@10.1.0. You can also ignore all packages with @SocketSecurity ignore-all. To ignore an alert for all future pull requests, use Socket's Dashboard to change the triage state of this alert.

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[phucnguyen1707]

Quick note on the Socket advisory comments: they come from sanitize-html's standard parser dependencies (htmlparser2/entities). I kept a maintained sanitizer here rather than a custom parser/regex because this PR is specifically closing an XSS sink. The Socket checks are successful, and I can switch sanitizer approach if you prefer another package.