docs: comprehensive documentation overhaul

Add complete documentation structure:
- Frontend architecture documentation
- Database schema documentation
- Deployment guides (Docker, Traefik, Authentik, Environment)
- Development guides (Setup, Testing, Contributing, Quality Gates)
- Deployment architecture documentation
- Updated docs README with complete navigation

All new features and APIs are now documented.
Quality gates: docs only, no code changes

docs/README.md

@@ -0,0 +1,72 @@
+# Headquarter Documentation
+
+Welcome to the Headquarter documentation. This is your central hub for understanding, using, and contributing to the platform.
+
+## Quick Links
+
+- [Features](features/) - Learn about available features
+- [API Reference](api/) - API endpoint documentation
+- [Architecture](architecture/) - System design and architecture
+- [Deployment](deployment/) - Setup and deployment guides
+- [Development](development/) - Development and contributing guides
+
+## Getting Started
+
+New to Headquarter? Start here:
+
+1. [Quick Start](../README.md#quick-start) - Get up and running
+2. [Features](features/) - Discover what you can do
+3. [Architecture](architecture/) - Understand the system
+
+## Documentation Structure
+
+### [Features](features/)
+User guides for each feature:
+- [Projects](features/projects.md) - Project management
+- [Repositories](features/repositories.md) - Git repository management
+- [Workspace](features/workspace.md) - Repository workspace
+- [Git History](features/git-history.md) - History visualization
+- [Authentication](features/auth.md) - Login and user management
+- [Settings](features/settings.md) - User preferences
+- [Tool Types](features/tool-types.md) - Development tool management
+- [SSH Keys](features/ssh-keys.md) - SSH key management
+
+### [API Reference](api/)
+Complete API documentation:
+- [Auth](api/auth.md) - Authentication endpoints
+- [Projects](api/projects.md) - Project endpoints
+- [Repositories](api/repositories.md) - Repository endpoints
+- [Users](api/users.md) - User endpoints
+- [Tool Types](api/tool-types.md) - Tool type endpoints
+- [SSH Keys](api/ssh-keys.md) - SSH key endpoints
+
+### [Architecture](architecture/)
+System architecture documentation:
+- [Backend](architecture/backend.md) - Backend architecture
+- [Frontend](architecture/frontend.md) - Frontend architecture
+- [Database](architecture/database.md) - Database schema
+- [Deployment](architecture/deployment.md) - Deployment architecture
+
+### [Deployment](deployment/)
+Guides for deploying Headquarter:
+- [Docker](deployment/docker.md) - Docker setup
+- [Traefik](deployment/traefik.md) - Traefik configuration
+- [Authentik](deployment/authentik.md) - Authentik setup
+- [Environment](deployment/environment.md) - Environment variables
+
+### [Development](development/)
+Guides for developers:
+- [Setup](development/setup.md) - Development environment
+- [Testing](development/testing.md) - Testing strategy
+- [Contributing](development/contributing.md) - How to contribute
+- [Quality Gates](development/quality-gates.md) - Code quality
+
+## Contributing to Documentation
+
+When adding new features, please document them following our [templates](templates/):
+
+- [Feature Documentation Template](templates/feature-doc.md)
+- [API Documentation Template](templates/api-endpoint.md)
+- [Architecture Documentation Template](templates/architecture.md)
+
+See the [Contributing Guide](development/contributing.md) for more details.