[Security] Harden takeRandomFromArray with CSPRNG

[gonzaloriestra]

This PR hardens the takeRandomFromArray utility function by replacing the insecure Math.random() with globalThis.crypto.getRandomValues().

Key changes:

• Switched to CSPRNG (globalThis.crypto.getRandomValues).
• Implemented rejection sampling to eliminate modulo bias.
• Added a guard for empty arrays to prevent errors.
• Added unit tests to verify the fix and ensure no regressions.

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PR created automatically by Jules for task 17267358148401281979 started by @gonzaloriestra

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