🔒 Fix Insecure Randomness for Cryptographic Salt in App.tsx

[jason420247]

🎯 What: Replaced the non-cryptographic Math.random() function used for generating salts in TrinityKeystore within App.tsx with a cryptographically secure implementation using crypto.getRandomValues().

⚠️ Risk: Math.random() is PRNG-based and predictable, allowing attackers to predict cryptographic salt values, which compromises keystore security and exposes cryptographic operations to prediction/replay attacks.

🛡️ Solution: Updated TrinityKeystore.getVector in App.tsx to utilize crypto.getRandomValues() with cross-environment resolution (supporting both window.crypto and globalThis.crypto). Added error handling if no cryptographically secure random number generator is available.

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PR created automatically by Jules for task 10892643076937377361 started by @jason420247

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