Add mock factories for test data

[gelluisaac]

Description

    Add mock factories for test data.

    ## Files to modify
    - packages/backend/src/services/
    - packages/client/app/

    ## Out of scope
    - Refactoring unrelated modules
    - Changing public API contracts
    - Major version bumps or breaking changes
    - Performance optimizations not directly related to the issue

    ## Acceptance criteria
    - [ ] Code changes implemented as per procedure steps
    - [ ] All new code has complete type hints
    - [ ] Unit tests added/updated with >90% coverage for changed code
    - [ ] All tests pass: npm test
    - [ ] Linting passes: npm run lint
    - [ ] Type checking passes: npm run typecheck
    - [ ] Documentation updated if needed
    - [ ] Changes reviewed and approved

[baling-1]

@baling-1 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello! I’d appreciate the opportunity to work on this issue. I’m an active contributor and can begin as soon as I’m assigned.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @baling-1 to this issue.

[Sadeequ]

@Sadeequ has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi there maintainer, let me get on this issue also as I solved the other one earlier will follow the rules you indicated I should follow SIR.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Sadeequ to this issue.

[drips-wave]

Congratulations, @Sadeequ! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @Sadeequ: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊