complete upgrade safety gate and add contract migration regression coverage

[grantfox-oss]

upgrade flow is partially documented, but the safety gate and rollback/migration invariants are not implemented end-to-end in the contract and tests.

• Impacted files: app/contract/contracts/Folder/src/storage.rs, app/contract/contracts/Folder/src/upgrade_test.rs, app/contract/contracts/Folder/src/lib.rs, app/contract/UPGRADE_SAFETY_GATE_IMPLEMENTATION.md, app/contract/UPGRADE_SAFETY_GATE_TEST_GUIDE.md, `app/contract/docs/UPGRADE_SAFETY_GATE.md

[tolulopedd26]

can i handle this?

[Violetlove200100]

I have experience reviewing code, writing tests, and working with Git. My approach will be to first understand the current upgrade safety gate implementation and the existing contract migration flow. I will identify any missing validation logic, implement the required safety checks, and add comprehensive regression tests to ensure contract migrations remain reliable and future changes do not introduce regressions.
Throughout the process, I'll keep the solution clean, well-tested, and aligned with the project's coding standards, while communicating my progress and asking questions whenever clarification is needed.

[grantfox-oss]

🦊 GrantFox — @tolulopedd26 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #318)
2. Your PR will be reviewed by the BlockDash-Studios maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@tolulopedd26's PR #322 was approved and merged by @MaryammAli.

🏆 @tolulopedd26: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (554 total points). Track your full progress on GrantFox.

👏 Great work, @tolulopedd26! Keep contributing to BlockDash-Studios.