🛡️ Sentinel: [MEDIUM] Enhance CSP with Trusted Types

[keough99]

🚨 Severity: MEDIUM
💡 Vulnerability: The current Content-Security-Policy does not mitigate DOM-based XSS attacks. While no unsafe DOM sinks (e.g., innerHTML) exist in the executed scripts, an attacker discovering a future vulnerability could execute arbitrary scripts.
🎯 Impact: A DOM XSS attack could compromise user sessions, steal data, or deface the static site. Adding trusted types provides a strong defense-in-depth mechanism.
🔧 Fix: Enhanced the <meta> CSP tags across all HTML files with require-trusted-types-for 'script'; trusted-types 'none'; to proactively block any dynamic string evaluation by DOM sinks.
✅ Verification: Verified locally that the CSP tags in the HTML files contain the new Trusted Types directives and all Playwright tests pass successfully without any JavaScript errors.

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PR created automatically by Jules for task 666429384006877790 started by @keough99

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