Indexer: Add API endpoints for task queries

[EDOHWARES]

Description

The frontend needs a way to query tasks efficiently. The indexer should expose a REST or GraphQL API.

Requirements

• Implement endpoints like /tasks/:id, /tasks/user/:address, and /tasks/recent.
• Include proper pagination and filtering options.

[ValJnr-dev1]

@ValJnr-dev1 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi Maintainer,

I’m a smart contract and full-stack developer and would love to contribute to this issue. I’m an experienced contributor with hands-on expertise in Rust, Soroban, Cairo, and TypeScript.

I’m passionate about building secure, scalable blockchain solutions, with a strong emphasis on writing clean and maintainable code. Based on the scope of this issue, I’m confident I can deliver a complete solution within 24 hours of assignment.

I’d greatly appreciate the opportunity to contribute and help move this forward.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @ValJnr-dev1 to this issue.

[Kenisank]

@Kenisank has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer, I would like to solve this issue

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

[JesseJohn7]

@JesseJohn7 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Please kindly assign me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @JesseJohn7 to this issue.