[Contracts] Implement Notification Expiration Logic

[Abd-Standard]

Description

Allow notifications stored on-chain to expire after a configurable duration.

Tasks
Add expiration timestamp support.
Prevent interaction with expired notifications.
Emit expiration events.
Write contract tests.

Acceptance Criteria
Expired notifications are invalid.
Events emit correctly.
Tests pass successfully.

[giftexceed]

I'd like to work on this issue.

I'm a TypeScript and blockchain developer with experience building and testing smart contracts, event-driven systems, and backend integrations. I have worked on contract state management, access control, lifecycle handling, and automated testing.

For this issue, I will implement configurable notification expiration logic, ensure expired notifications can no longer be interacted with, emit the appropriate contract events, and add comprehensive tests covering both valid and expired states. My focus will be on correctness, security, and maintainability while ensuring the feature integrates cleanly with the existing contract architecture.

[grantfox-oss]

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

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #128)
2. Your PR will be reviewed by the Core-Foundry 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 campaign!

@giftexceed's PR #157 was approved and merged by @Abd-Standard.

🏆 @giftexceed: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (293 total points). Track your full progress on GrantFox.

👏 Great work, @giftexceed! Keep contributing to Core-Foundry.