🔒 Fix Insecure Randomness for Cryptographic Salt in App.tsx

[jason420247]

🎯 What: Replaced the non-cryptographic pseudo-random number generator Math.random() in TrinityKeystore.getVector in App.tsx with window.crypto.getRandomValues / globalThis.crypto.getRandomValues.

⚠️ Risk: Math.random() produces predictable pseudorandom sequences, which makes cryptographic salt generation vulnerable to prediction and brute-force attacks.

🛡️ Solution: Uses Web Crypto API's getRandomValues via Uint32Array with proper global context fallback checks (window / globalThis), ensuring high-entropy, unpredictable salts.

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PR created automatically by Jules for task 14204307827180801289 started by @jason420247

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