[EPIC-16] API Documentation & Developer Experience

[leimo2011]

📖 Epic: API Documentation & Developer Experience

Objective: Comprehensive, always-up-to-date API documentation for internal and future external developers.

Scope

• OpenAPI 3.0 spec (auto-generated from Django)
• Swagger UI / Redoc hosted docs
• Postman collection
• Authentication guide
• Webhook documentation
• Rate limiting documentation
• Changelog
• SDK considerations (future)

Repos: liemo-docs, liemo-api

Milestone: M1 - Alpha

Acceptance Criteria

• All API endpoints documented in OpenAPI spec
• Swagger UI accessible at /api/docs
• Postman collection importable and working
• Changelog maintained per release