feat(contracts): implement claim timelock and disputes holding window

[Dopezapha]

Closes #841

PR Description

This PR implements a disputes holding window (claim timelock) for the digital inheritance contracts.

When a payout is triggered by calling claim, the funds do not leave the contract immediately. Instead, the contract records the claim's timestamp in persistent storage (ClaimStatus) to start the timelock grace window. During this lock period, if the owner is still active or disputes the claim, they can call cancel_claim to reset the inactivity timer and reactivate the plan, or call reclaim to withdraw all vault assets back to their wallet and delete the plan.

After the configured timelock duration expires, trigger_payout can be called (pulled) to execute the asset distribution to beneficiaries.

Changes Made

• Modified contracts/inheritance-contract/src/lib.rs:
  • Added timelock_duration to the Plan struct and updated create_plan to configure it.
  • Updated claim to store the start of the timelock in persistent storage under ClaimStatus with the current ledger timestamp.
  • Added cancel_claim allowing the owner to delete the claim lock and reactivate the plan.
  • Added reclaim allowing the owner to cancel the lock, delete the plan, and withdraw all vault assets.
  • Modified trigger_payout to verify the timelock has expired before distributing the funds.
  • Added TimelockNotExpired and PayoutNotTriggered error variants.
• Modified contracts/inheritance-contract/src/test.rs:
  • Updated existing tests to pass the new timelock_duration argument and test sequences.
  • Added test_cancel_claim_success and test_reclaim_success unit tests.

Testing

Run the contract unit tests using Cargo:

cargo test --manifest-path contracts/inheritance-contract/Cargo.toml

Result: All 15 tests passed successfully.

[drips-wave]

@Dopezapha Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[ONEONUORA]

@Dopezapha
Run cargo fmt --all -- --check
and clippy