feat: add marketplace metrics, privacy features, and service registry endpoints

- Add Prometheus metrics for marketplace API throughput and error rates with new dashboard panels
- Implement confidential transaction models with encryption support and access control
- Add key management system with registration, rotation, and audit logging
- Create services and registry routers for service discovery and management
- Integrate ZK proof generation for privacy-preserving receipts
- Add metrics instru

docs/developer/index.md

@@ -0,0 +1,46 @@
+# AITBC Developer Documentation
+
+Welcome to the AITBC developer documentation. This section contains resources for building on AITBC.
+
+## Getting Started
+
+- [Overview](overview.md) - Developer platform overview
+- [Setup](setup.md) - Development environment setup
+- [Contributing](contributing.md) - How to contribute to AITBC
+
+## API Documentation
+
+- [API Overview](api/overview.md) - REST API introduction
+- [Authentication](api/authentication.md) - API authentication guide
+- [Endpoints](api/endpoints.md) - Available API endpoints
+- [OpenAPI Spec](api/openapi.md) - OpenAPI specification
+
+## SDKs
+
+- [Python SDK](sdks/python.md) - Python SDK documentation
+- [JavaScript SDK](sdks/javascript.md) - JavaScript SDK documentation
+
+## Tutorials & Examples
+
+- [Examples](examples.md) - Code examples and tutorials
+- [API Authentication](api-authentication.md) - Authentication examples
+
+## Architecture
+
+- [Architecture Guide](../reference/architecture/) - System architecture documentation
+- [Design Patterns](../reference/architecture/) - Common patterns and best practices
+
+## Testing
+
+- [Testing Guide](testing.md) - How to test your AITBC applications
+- [Test Examples](../examples/) - Test code examples
+
+## Deployment
+
+- [Deployment Guide](../operator/deployment/) - How to deploy AITBC applications
+- [CI/CD](../operator/deployment/) - Continuous integration and deployment
+
+## Reference
+
+- [Glossary](../reference/glossary.md) - Terms and definitions
+- [FAQ](../user-guide/faq.md) - Frequently asked questions