[Docs] Write a complete backend API reference (endpoints, auth, payloads, errors)

[grantfox-oss]

Telegram (ask questions / claim the issue here first): https://t.me/+DOylgFv1jyJlNzM0

Why this matters

There is no API reference anywhere in the docs repo, yet the backend exposes many routes (loans, pool, remittances, score, notifications, admin, indexer, auth). Contributors and integrators have to read the source to learn the API surface, auth model, and error shapes.

Acceptance criteria

• Document every public endpoint grouped by domain, with method, path, auth requirement, request schema, and response schema
• Document the auth models (JWT bearer, internal API key) and which endpoints use which
• Document the standardized error response shape and common error codes
• Note idempotency and rate-limit behavior where it applies

Files to touch

• api-reference.md (new)
• wiki/README.md

Out of scope

• Auto-generating from OpenAPI (can be a follow-up)
• Client SDK docs

[Banx17]

I have experience with similar tasks and I'm confident I can investigate, implement a clean solution, and thoroughly test it before submitting a PR. If the issue is still open, I would appreciate it if you could assign it to me. Thank you

[gloskull]

Hello, I have 4 years of experience delivering solutions for projects like this, covering backend, frontend, and smart contract development. After carefully reviewing your requirements, I have a clear understanding of the task and am confident in my ability to deliver a clean, efficient, and thoroughly tested solution on time. I prioritize code quality, maintainability, and industry best practices throughout the development process.

[dubemoyibe-star]

I'd like to work on this issue.

I'll create a comprehensive API reference covering all public endpoints, grouped by domain, with authentication requirements, request/response schemas, and relevant usage notes. I'll also document the authentication models, standardized error responses, common error codes, and any idempotency or rate-limiting behavior where applicable.

In addition, I'll update the wiki documentation so contributors and integrators have a clear starting point without needing to dig through the source code.

[grantfox-oss]

🦊 GrantFox — @dubemoyibe-star has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #2)
2. Your PR will be reviewed by the LabsCrypt maintainers

Good luck! Track your progress on GrantFox.