docs: Restructure documentation with Bookstack-compatible hierarchy

- Organized docs into numbered shelf/book/chapter/page structure
- Created comprehensive README.md with project overview
- Added Getting Started book (quick start, installation, configuration)
- Added Development book (workflow, testing, type sharing)
- Added Architecture book (design principles, PDA-friendly patterns)
- Added API Reference book (conventions, authentication)
- Moved TYPE-SHARING.md to proper location
- Updated all cross-references in main README
- Created docs/README.md as master index
- Removed old QA automation reports
- Removed deprecated SETUP.md (content split into new structure)

Documentation structure follows Bookstack best practices:
- Numbered books: 1-getting-started, 2-development, 3-architecture, 4-api
- Numbered chapters and pages for ordering
- Clear hierarchy and navigation
- Cross-referenced throughout

Complete documentation available at: docs/README.md

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/1-getting-started/1-quick-start/1-overview.md

@@ -0,0 +1,77 @@
+# Quick Start
+
+Get Mosaic Stack running in 5 minutes with Docker.
+
+## Prerequisites
+
+- Docker 24+ and Docker Compose 2.20+
+- Git 2.x
+
+## Installation
+
+```bash
+# Clone repository
+git clone https://git.mosaicstack.dev/mosaic/stack mosaic-stack
+cd mosaic-stack
+
+# Copy environment file
+cp .env.example .env
+
+# Start all services
+docker compose up -d
+
+# Run migrations
+docker compose exec api pnpm prisma migrate deploy
+
+# Seed development data (optional)
+docker compose exec api pnpm prisma:seed
+```
+
+## Verify Installation
+
+```bash
+# Check API health
+curl http://localhost:3001/health
+
+# Expected response:
+# {"status":"ok","timestamp":"...","uptime":...}
+
+# View logs
+docker compose logs -f api
+```
+
+## What's Running?
+
+| Service | Port | Purpose |
+|---------|------|---------|
+| API | 3001 | NestJS backend |
+| PostgreSQL | 5432 | Database |
+| Valkey | 6379 | Cache (Redis-compatible) |
+
+## Next Steps
+
+1. **Configure Authentication** — See [Configuration → Authentik](../3-configuration/2-authentik.md)
+2. **Explore the API** — Check [API Reference](../../4-api/README.md)
+3. **Start Developing** — Read [Development → Workflow](../../2-development/1-workflow/1-branching.md)
+
+## Troubleshooting
+
+**Port already in use:**
+```bash
+# Stop existing services
+docker compose down
+
+# Check what's using the port
+lsof -i :3001
+```
+
+**Database connection failed:**
+```bash
+# Check PostgreSQL is running
+docker compose ps postgres
+
+# View PostgreSQL logs
+docker compose logs postgres
+```
+
+For detailed installation options, see [Installation → Local Setup](../2-installation/2-local-setup.md).