⚡ Bolt: Optimize verifier HMAC initialization

[ightevenmckane187]

💡 What: Hoisted the static evaluation window constant (PERFORMANCE_WINDOW) to the module scope and replaced the slow String(salt) constructor with the fast coercive pattern "" + salt for HMAC matrix initialization in src/crypto/verifier.ts and src/crypto/proofGenerator.ts.
🎯 Why: To eliminate unneeded scope allocations, function call overhead, and CPU overhead on high-frequency cryptographic verification and generation hot-paths.
📊 Impact: Expect faster throughput on cryptographic verifications by reducing garbage collection pressure and function invocation overhead in V8.
🔬 Measurement: Can be verified by running the verifier benchmark suite (npx tsx benchmarks/verifier_bench.ts).

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PR created automatically by Jules for task 4778943377675356665 started by @ightevenmckane187

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