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/user-guide/explorer.md

@@ -0,0 +1,46 @@
+---
+title: Explorer
+description: Using the AITBC blockchain explorer
+---
+
+# Explorer
+
+The AITBC explorer allows you to browse and search the blockchain for transactions, jobs, and other activities.
+
+## Features
+
+### Transaction Search
+- Search by transaction hash
+- Filter by address
+- View transaction details
+
+### Job Tracking
+- Monitor job status
+- View job history
+- Analyze performance
+
+### Analytics
+- Network statistics
+- Volume metrics
+- Activity charts
+
+## Using the Explorer
+
+### Web Interface
+Visit [https://explorer.aitbc.io](https://explorer.aitbc.io)
+
+### API Access
+```bash
+# Get transaction
+curl https://api.aitbc.io/v1/transactions/{tx_hash}
+
+# Get job details
+curl https://api.aitbc.io/v1/jobs/{job_id}
+```
+
+## Advanced Features
+
+- Real-time updates
+- Custom dashboards
+- Data export
+- Alert notifications