🛡️ Sentinel: Fix syntax errors and memory hazards in PersistenceLayer

[ightevenmckane187]

🛡️ Sentinel Security Fix

• Severity: MEDIUM
• Vulnerability: Uninitialized heap memory leak risk when serializing state via Buffer.allocUnsafe(), alongside broken code references/syntax errors in src/os/persistence/PersistenceLayer.ts.
• Impact: Buffer.allocUnsafe() allocates uninitialized buffer memory that could potentially expose sensitive residual heap data if not completely overwritten. Syntax errors caused test failures in persistence security test suites.
• Fix: Switched allocation from Buffer.allocUnsafe to Buffer.alloc to guarantee zeroed buffer memory allocation. Cleaned up syntax errors and dead code references.
• Verification: Ran full test suites (npx jest --testPathIgnorePatterns="tests/unit" and npx vitest run tests/unit), ESLint, and Prettier checks.

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PR created automatically by Jules for task 1432282714752184482 started by @ightevenmckane187

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