Notion ticket link

N/A

Implementation description

• Added sample GraphQL schema, resolvers, and service layer for CRUD operations on Sample entities.
• Integrated Sequelize ORM and downgraded express to 4.18.2 to resolve apollo-server-express dependency conflict.
• Cleaned up lint errors and formatted backend code.

Steps to test

1. Run npm install in backend directory.
2. Start backend server and verify GraphQL endpoints for Sample work (query, mutation).
3. Run linter and formatter to confirm no errors.
4. Check CI workflow for successful dependency installation.

What should reviewers focus on?

• Correctness of GraphQL schema and resolver logic.
• Dependency compatibility (express and apollo-server-express).
• Code style and lint compliance.

Checklist

• My PR name is descriptive and in imperative tense
• My commit messages are descriptive and in imperative tense. My commits are atomic and trivial commits are squashed or fixup'd into non-trivial commits
• I have run the appropriate linter(s)
• I have requested a review from the PL, as well as other devs who have background knowledge on this PR or who will be building on top of this PR