23 Donation e2e integration and controller unit testing

[SamNie2027]

Description

Donation Controller Unit tests for the POST /api/donations, GET /api/donations/public, and GET /api/donations/stats endpoints
Donation e2e integration tests for the POST /api/donations, GET /api/donations/public, and GET /api/donations/stats endpoints

Testing & Verification

Smoke test to validate test setup

1. POST /api/donations - successful one-time donation creation
2. POST /api/donations - successful recurring donation with interval
3. POST /api/donations - validation errors:
4. Negative amount returns 400
5. Invalid email format returns 400
6. Donation marked recurring without a specified interval returns 400
7. One-time with interval returns 400
8. Throws 500 if the database errors
9. Rejects with missing first name
10. Rejects with missing last name
11. Rejects with missing email
12. Rejects with missing amount
13. Accepts if isAnonymous is missing
14. Rejects with missing donationType
15. Rejects with invalid recurring
16. Rejects with invalid donationType
17. GET /api/donations/public - returns only non-anonymous donations
18. Returns no donations if there are none in the db
19. Throws if db does
20. Returns with correct DTO
21. GET /api/donations/stats - returns correct total and count
22. Returns correct total and count even with empty db
23. throws if db throws

Related Issues

Closes #23