🔒 Fix Insecure Randomness for Cryptographic Salt in App.tsx

[jason420247]

🎯 What: Ensure TrinityKeystore.getVector in App.tsx generates cryptographically secure salt vectors using the Web Crypto API (crypto.getRandomValues) rather than Math.random(). Added JSDoc documentation to prevent future security regressions.

⚠️ Risk: Weak or predictable random salts generated by Math.random() could allow attackers to predict key/vector components generated by the Trinity Keystore system, compromising vector integrity and cryptographic security.

🛡️ Solution: TrinityKeystore.getVector utilizes crypto.getRandomValues via Web Crypto API with fallback detection (window.crypto or globalThis.crypto). Added JSDoc security documentation.

---

PR created automatically by Jules for task 17725849864255055340 started by @jason420247

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.