8. Add storage persistence audit

[DeFiVC]

What: Audit storage persistence levels (persistent, temporary, instance) and ensure correct usage.

Why: Incorrect persistence levels can cause data loss or unnecessary costs.

Scope: Review all storage operations. Verify persistence levels are correct. Fix any misconfigurations.

Acceptance criteria:

• All storage is reviewed
• Persistence levels are correct
• Misconfigurations are fixed
• Costs are optimized

Technical context: All contract source files.

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