chore: standardize configuration, logging, and error handling across blockchain node and coordinator API

- Add infrastructure.md and workflow files to .gitignore to prevent sensitive info leaks
- Change blockchain node mempool backend default from memory to database for persistence
- Refactor blockchain node logger with StructuredLogFormatter and AuditLogger (consistent with coordinator)
- Add structured logging fields: service, module, function, line number
- Unify coordinator config with Database

docs/5_reference/15_skipped-tests-roadmap.md

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+# Skipped Integration Tests - Roadmap Status
+
+## Overview
+Several integration tests are skipped because the features are not yet fully implemented. Here's the status of each:
+
+## 1. Wallet Integration Tests
+**Test**: `test_job_payment_flow` in `TestWalletToCoordinatorIntegration`
+**Status**: ⚠️ **PARTIALLY IMPLEMENTED**
+- **Roadmap Reference**: Stage 11 - Trade Exchange & Token Economy [COMPLETED: 2025-12-28]
+- **Completed**: 
+  - ✅ Bitcoin payment gateway for AITBC token purchases
+  - ✅ Payment request API with unique payment addresses
+  - ✅ QR code generation for mobile payments
+  - ✅ Exchange payment endpoints (/api/exchange/*)
+- **Missing**: Full integration between wallet daemon and coordinator for job payments
+
+## 2. Marketplace Integration Tests
+**Test**: `test_service_listing_and_booking` in `TestMarketplaceIntegration`
+**Status**: ✅ **IMPLEMENTED**
+- **Roadmap Reference**: Stage 3 - Pool Hub & Marketplace [COMPLETED: 2025-12-22]
+- **Completed**:
+  - ✅ Marketplace web scaffolding
+  - ✅ Auth/session scaffolding
+  - ✅ Production deployment at https://aitbc.bubuit.net/marketplace/
+- **Note**: Test infrastructure needs updating to connect to live marketplace
+
+## 3. Security Integration Tests
+**Test**: `test_end_to_end_encryption` in `TestSecurityIntegration`
+**Status**: ✅ **IMPLEMENTED**
+- **Roadmap Reference**: Stage 12 - Zero-Knowledge Proof Implementation [COMPLETED: 2025-12-28]
+- **Completed**:
+  - ✅ ZK proof service integration with coordinator API
+  - ✅ ZK proof generation in coordinator service
+  - ✅ Confidential transaction support
+- **Note**: Test infrastructure needs updating to use actual security features
+
+## 4. Performance Integration Tests
+**Tests**: 
+- `test_high_throughput_job_processing` in `TestPerformanceIntegration`
+- `test_scalability_under_load` in `TestPerformanceIntegration`
+**Status**: 🔄 **PARTIALLY IMPLEMENTED**
+- **Roadmap Reference**: Multiple stages
+- **Completed**:
+  - ✅ Performance metrics collection (Stage 4)
+  - ✅ Autoscaling policies (Stage 5)
+  - ✅ Load testing infrastructure
+- **Missing**: Dedicated performance test suite with specific thresholds
+
+## Recommendations
+
+### Immediate Actions
+1. **Update Marketplace Test**: Connect test to the live marketplace endpoint
+2. **Update Security Test**: Use actual ZK proof features instead of mocks
+3. **Implement Performance Tests**: Create proper performance test suite with defined thresholds
+
+### For Wallet Integration
+The wallet daemon exists but the coordinator integration for job payments needs to be implemented. This would involve:
+- Adding payment endpoints to coordinator API
+- Integrating wallet daemon for payment processing
+- Adding escrow functionality for job payments
+
+### Test Infrastructure Improvements
+- Set up test environment with access to live services
+- Create test data fixtures for marketplace and security tests
+- Implement performance benchmarks with specific thresholds
+
+## Next Steps
+1. Prioritize wallet-coordinator integration (critical for job payment flow)
+2. Update existing tests to use implemented features
+3. Add comprehensive performance test suite
+4. Consider adding end-to-end tests that span multiple services