🛡️ Sentinel: [HIGH] Fix DOM-based mXSS vulnerability in dashboard UI

[tody-agent]

🚨 Severity: HIGH
💡 Vulnerability: DOM-based Mutation XSS (mXSS). The project previously used document.createElement('div'); d.textContent = str; return d.innerHTML; for sanitization in public/dashboard/app.js. This approach is known to be vulnerable to mXSS depending on browser-specific DOM parsing rules, especially when innerHTML reflects content into attributes, failing to escape quotation marks (" and ').
🎯 Impact: An attacker could break out of attributes using quotes and inject malicious scripts (XSS).
🔧 Fix: Replaced the DOM-based method with a robust regex string replacement method that correctly escapes all HTML-sensitive characters (&, <, >, ", '). Logged this critical security learning in .jules/sentinel.md.
✅ Verification: Ran npm run test:gate which successfully passed. Verified the esc() function in the frontend.

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PR created automatically by Jules for task 13856266456821668909 started by @tody-agent

[google-labs-jules]

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