🛡️ Sentinel: [HIGH] Enhance CSP with Trusted Types

[keough99]

🚨 Severity: HIGH
💡 Vulnerability: The application currently lacks Trusted Types enforcement in its Content-Security-Policy, leaving it potentially vulnerable to DOM-based XSS attacks if unsafe DOM sinks (like innerHTML) are ever introduced.
🎯 Impact: Without Trusted Types, an attacker could potentially inject malicious scripts via DOM sinks, leading to data theft, session hijacking, or defacement.
🔧 Fix: Added require-trusted-types-for 'script'; trusted-types 'none'; to the Content-Security-Policy in all HTML files to strictly enforce safe DOM manipulation and completely block DOM-based XSS.
✅ Verification: Verified the presence of the updated Content-Security-Policy meta tag in index.html, how-to-join.html, socials.html, why-donate.html, and wiki.html, and ensured the static site continues to function correctly by running existing tests.

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PR created automatically by Jules for task 16130095803469331168 started by @keough99

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