Implement GraphQL federation gateway for API aggregation

[Smartdevs17]

Description

Build a GraphQL federation gateway that unifies multiple backend services (payments, disputes, analytics, users) under a single API endpoint, reducing client complexity.

Acceptance Criteria

• Apollo Federation setup with type merging across services
• Persisted queries for production optimization
• Query cost analysis and depth limiting
• Rate limiting per federated service
• Schema registry with versioned schemas
• Federation tracing and performance monitoring

Technical Scope

• backend/src/graphql/gateway.ts
• backend/src/graphql/schema.ts
• backend/src/graphql/persisted-queries.ts
• backend/src/graphql/plugins/cost-analysis/
• Edge: circular type references, partial service availability, cache invalidation

[OmniZlatoon]

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

Good day maintainer, please I am committed to my work on drips and I assure you the job completion on time .I would love to work on this issue maintainer. Please Assign me and I'll get the job done.

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[Johnpii1]

@Johnpii1 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hello Sir,

I recently came across your project and I’m very interested in contributing to the team.

I have experience working with React to build responsive and user-friendly interfaces, and I also have a solid understanding of smart contracts and blockchain fundamentals. I enjoy writing clean, scalable code and focusing on improving overall user experience.

I’m a fast learner, highly motivated, and available to get started immediately. I would appreciate the opportunity to contribute and would be glad to discuss the next steps.

Thank you for your time and consideration. I look forward to hearing from you.

Best regards,
Johnpaul

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Johnpii1 to this issue.

[AgilityB]

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

Hi Lead, let me work on this issue

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