🛡️ Sentinel: [HIGH] Fix DOM-based XSS vulnerability via missing Trusted Types

[keough99]

🚨 Severity: HIGH
💡 Vulnerability: The application was vulnerable to potential DOM-based Cross-Site Scripting (XSS) due to a lack of Trusted Types enforcement.
🎯 Impact: If a DOM XSS vulnerability were to be introduced, attackers could execute arbitrary JavaScript.
🔧 Fix: Added require-trusted-types-for 'script'; trusted-types 'none'; to the Content-Security-Policy meta tag in all HTML files to block string execution in unsafe DOM sinks.
✅ Verification: Ensured the CSP meta tag contains the new directives and ran the existing test suite successfully.

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PR created automatically by Jules for task 11616794615383213129 started by @keough99

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