[Backend] -- Add GraphQL API Endpoint

[Devsol-01]

Description

Implement GraphQL API alongside REST for flexible data querying.

Tasks

• Install @nestjs/graphql
• Set up Apollo Server
• Create GraphQL schemas
• Implement resolvers
• Add authentication
• Set up GraphQL Playground
• Add subscriptions support

Acceptance Criteria

• GraphQL endpoint works
• Queries return data
• Mutations work
• Playground accessible

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[victorEdeh]

@victorEdeh has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

i will like to work on the issue

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

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Congratulations, @victorEdeh! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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[drips-wave]

This issue has been completed by @victorEdeh as part of the Stellar Wave Program's 5th Wave 🥳

😎 @victorEdeh: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

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