Implement Donation Status State Machine

[grantfox-oss]

Description:
Model the donation lifecycle as an explicit state machine in Rust.

Tasks:

• Create src/models/donation_status.rs
• Define DonationStatus enum: Pending, Submitted, Confirming, Confirmed, Failed, Refunded
• Implement DonationStatus::transition(event: DonationEvent) -> Result<DonationStatus, TransitionError>
• Reject invalid state transitions (e.g. Confirmed → Pending)
• Use this state machine in all donation update flows

Acceptance Criteria:
Invalid state transitions return an error; valid transitions update the status correctly.

---

[soundsng]

Hey maintainer. I have a proven track record and already understand the codebase and how to implement this issue without obstacles.

[Muhamadmust]

Hi
I have reviewed this issue and would love to work on it, PR 2 days

[Mystery-CLI]

I have read through the required implementations and understand what to do can i work on it?

[Mystery-CLI]

I have read through the required implementations and understand what to do can i work on it?

[grantfox-oss]

🦊 GrantFox — @soundsng 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 #54)
2. Your PR will be reviewed by the Dfunder maintainers

Good luck! Track your progress on GrantFox.