Add storage-tier classifier audit

[greatest0fallt1me]

Description

This is a smart-contract issue for the GrantFox campaign. This is a smart-contract issue for the GrantFox campaign. Audit and document the storage tier for every data key.

Requirements and Context

• Implement per the description
• Add focused tests for the change
• Document any API/visible changes
• Adhere to repo's lint and code style
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b task/storage-tier-audit

2. Implement changes
   • docs/STORAGE_TIER_AUDIT.md (new)
   • contracts/predictify-hybrid/src/storage.rs
3. Test and commit
   • Run the repo's standard test suite and lint
   • Cover edge cases; include output in the PR

Example commit message

docs: storage tier audit

Acceptance Criteria

• Implementation matches the description
• Tests added and passing
• Code review approved
• Docs updated

Guidelines

• Minimum 95% test coverage with cargo test
• require_auth on every state-changing entrypoint
• Overflow-safe math; no unwrap() in production paths
• Clear NatSpec-style /// rustdoc
• Timeframe: 96 hours

[mikewheeleer]

I would like to work on this issue, and I have good knowledge of smart contacts and Sorabani Rust. Kindly assign it to me.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@mikewheeleer's PR #787 was approved and merged by @greatest0fallt1me.

🏆 @mikewheeleer: You earned 40 FoxPoints for this contribution! Your current tier: Builder (2,708 total points). Track your full progress on GrantFox.

👏 Great work, @mikewheeleer! Keep contributing to Predictify-org.