[Issue]: Finalize tests in both GraphQL and REST

[soramicha]

Branch Name

feature/66-crud-rest-graphql-chapter-project

Task

We missed some CRUD tests such as DELETE tests for Chapter and Project's REST and GraphQL!

Add them! Also make sure that there are NO remaining rows created on the Supabase after all tests RUN.

Make sure every test in both REST and GraphQL have these:

• POST
• UPDATE/PATCH
• GET
• GET BY ID
• DELETE

Acceptance Criteria

• All REST and GraphQL API tests have POST, UPDATE/PATCH, GET, GET BY ID, and DELETE tests
• No remaining rows in all tables on Supabase (basically all CRUD operations per API are tested)

Checklist

• I have checked for duplicate issues.
• I have assigned the issue to the correct project board.
• I have tagged the issue properly.

Code of Conduct

• I agree to follow this project's Code of Conduct