Add comprehensive API documentation with OpenAPI/Swagger

[DeFiVC]

What

The API lacks comprehensive documentation describing all endpoints, request/response formats, and authentication requirements.

Why

• New developers don't know what endpoints are available
• Frontend developers need to know exact request/response formats
• No way to test endpoints without reading source code

Scope

Generate OpenAPI documentation from the existing Fastify routes.

Acceptance Criteria

• OpenAPI spec auto-generated from route definitions
• Swagger UI available at /docs endpoint
• All endpoints documented with schemas
• Authentication requirements documented
• Error response formats documented

Technical Context

• Framework: Fastify
• Package: @fastify/swagger or similar
• Location: Add to src/server.ts
• Pattern: Fastify has built-in Swagger support

[GABRIELOFGOD]

Please assign to me, I will fix it.

[yustech-alt]

@yustech-alt has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi Maintainer, I’d like to work on this issue. I have experience handling similar tasks and can start immediately.

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

[0takuc0mrade]

@0takuc0mrade has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi maintainer, I'd like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @0takuc0mrade to this issue.

[Tobi-8]

@Tobi-8 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

please maintainer , assign me to this issue. I have looked through your description, and i have had experience in this type of issue.
kindly assign

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Tobi-8 to this issue.

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Congratulations, @0takuc0mrade! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@0takuc0mrade's PR #420 was approved and merged by @DeFiVC.

🏆 @0takuc0mrade: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (780 total points). Track your full progress on GrantFox.

👏 Great work, @0takuc0mrade! Keep contributing to ChainLearnOfficial.

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This issue has been completed by @0takuc0mrade as part of the Stellar Wave Program's 8th Wave 🥳

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