🛡️ Sentinel: Fix Stored XSS in Markdown Parser

[google-labs-jules]

🛡️ Sentinel Report: Stored XSS Fix

Vulnerability:
The ArticlePage.tsx component used a custom regex-based markdown parser that directly injected HTML into the DOM via dangerouslySetInnerHTML. The parser lacked input sanitization, allowing attackers (or malicious content sources) to break out of generated tags (e.g., using </pre><script>...) and execute arbitrary JavaScript.

Fix:
Implemented an escapeHtml function that converts special characters (&, <, >, ", ') to their HTML entities. This function is applied to the raw article content before any markdown processing occurs.

Impact:

• Security: XSS vector is neutralized. Malicious tags render as plain text.
• Functionality: Markdown syntax (bold, headers, code blocks) continues to work. Code blocks now safely display HTML-like content (e.g., print("<div>") renders as visible text).
• Verification: Verified with a reproduction script and Playwright visual test. All existing tests passed.

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PR created automatically by Jules for task 16053209843193932100 started by @albertoivo

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