⚡ Bolt: Replace map format hex encoding with hex::encode

[Tcode-Motion]

💡 What:
Replaced the iterative .iter().map(|b| format!("{:02x}", b)).collect::<String>() hex string generation in stdlib/src/crypto.rs and stdlib/src/security.rs with hex::encode().

🎯 Why:
The previous implementation suffered from severe performance overhead due to allocating a new intermediate String object for every single byte processed via format!. Using hex::encode() eliminates all intermediate allocations, generating the full hex string into a single, correctly-sized buffer.

📊 Measured Improvement:
Replaces N temporary string allocations with exactly 1 string allocation per cryptographic operation.

🔬 Measurement:
Run cargo test -p techscript_stdlib to confirm cryptographic behaviors remain unaffected. No regressions were found during cargo test --workspace --all-targets.

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PR created automatically by Jules for task 17363716070361557883 started by @Tcode-Motion

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