[ISSUE-048] Documentation

## Phase 8: Testing & Deployment (Week 12)

### Description
Write API documentation (Swagger/OpenAPI)
Create user guide and tutorials
Document architecture and deployment
Add inline code documentation
Create README files

### Can Work in Parallel With
- #046
- #047

No files, tests, API entry points, or deployment configuration are named. Start by inventorying the existing API, deployment setup, README files, and inline documentation, then define the documentation scope and review path. Done means the Swagger/OpenAPI reference, user guide, tutorials, architecture and deployment documentation, inline comments, and README files are complete.

Written by the indexing model from the issue text.