Add developer onboarding docs covering local setup and API endpoint reference

[Chucks1093]

Summary

New contributors face two friction points: no documented path to get the server running locally, and no reference for what endpoints exist and what they return. Both docs should live in the same docs/ directory and be cross-linked.

Scope

• Local setup guide: prerequisites with versions, numbered steps for clone → install → env → migrate → seed, separate start commands for the API server and the indexer, verification steps (expected health check response and first creator list response)
• API endpoint reference: list every public endpoint with method, path, query parameters, authentication requirement, and a sample response for the happy path; flag any endpoints that require a connected wallet

Acceptance Criteria

• Setup guide prerequisites include Node version and database engine
• Setup steps are numbered and sequential with no assumed knowledge
• API and indexer start commands both documented
• Verification steps confirm a working local environment
• API reference covers all public endpoints
• Each endpoint entry includes method, path, params, auth requirement, and sample response
• Both documents cross-linked from each other

ETA: 12 hours

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Coordinate on Telegram

[Mona-i]

Hey

i Would love to work on this issue

[wheval]

Hello i would love to work on this.