🔒 Fix Insecure Randomness for Cryptographic Salt in App.tsx

[jason420247]

🎯 What: Replaced the use of Math.random() in TrinityKeystore.getVector() in App.tsx with a cryptographically secure random number generator (crypto.getRandomValues).

⚠️ Risk: Math.random() is a non-cryptographic pseudo-random number generator whose outputs can be predictable. Using it for cryptographic salts or vector identifiers introduces predictability vulnerabilities, exposing keystore vectors or salts to potential entropy exploitation or brute-force prediction attacks.

🛡️ Solution: Used crypto.getRandomValues() via a safe cross-environment resolution (supporting window.crypto and globalThis.crypto) to generate cryptographically strong pseudo-random values for salts in TrinityKeystore.

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PR created automatically by Jules for task 17717106603480766443 started by @jason420247

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