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

apps/miner-node/plugins/__init__.py

@@ -0,0 +1,15 @@
+"""
+Miner plugin system for GPU service execution
+"""
+
+from .base import ServicePlugin, PluginResult
+from .registry import PluginRegistry
+from .exceptions import PluginError, PluginNotFoundError
+
+__all__ = [
+    "ServicePlugin",
+    "PluginResult", 
+    "PluginRegistry",
+    "PluginError",
+    "PluginNotFoundError"
+]