Add core service infrastructure

- NATS event bus (pub/sub, JetStream, KV storage)
- Service registry with health monitoring
- Base service class with lifecycle management
- Config system
- Logger with Vi formatting

Adapted from Lyra's patterns, namespace changed to vi.*

🦊💕

core/config.py

@@ -0,0 +1,94 @@
+import json
+import os
+from pathlib import Path
+from typing import Dict, Any
+
+
+class Config:
+    _instance = None
+    _config_data = None
+
+    def __new__(cls):
+        if cls._instance is None:
+            cls._instance = super().__new__(cls)
+        return cls._instance
+
+    def __init__(self):
+        if self._config_data is None:
+            self._load_config()
+
+    def _load_config(self):
+        config_path = os.path.join(os.path.dirname(__file__), '..', 'config', 'config.json')
+        config_path = os.path.abspath(config_path)
+        
+        try:
+            with open(config_path, 'r') as f:
+                self._config_data = json.load(f)
+        except FileNotFoundError:
+            # Default config if file doesn't exist
+            self._config_data = {
+                'nats': {
+                    'url': 'nats://localhost:4222',
+                    'connection_timeout': 30,
+                    'max_reconnect_attempts': 10
+                }
+            }
+        except json.JSONDecodeError as e:
+            raise ValueError(f"Invalid JSON in configuration file: {e}")
+
+    def get(self, key: str, default: Any = None) -> Any:
+        keys = key.split('.')
+        value = self._config_data
+        
+        for k in keys:
+            if isinstance(value, dict) and k in value:
+                value = value[k]
+            else:
+                return default
+        
+        return value
+
+    @property
+    def nats_url(self) -> str:
+        return os.getenv('NATS_URL') or self.get('nats.url', 'nats://localhost:4222')
+
+    @property
+    def nats_connection_timeout(self) -> int:
+        return self.get('nats.connection_timeout', 30)
+
+    @property
+    def nats_max_reconnect_attempts(self) -> int:
+        return self.get('nats.max_reconnect_attempts', 10)
+
+    def get_local_services(self) -> list:
+        """Get list of services that should run on this node"""
+        systemd_services = self.get('auto_upgrade.systemd_services', [])
+        local_services = []
+        for systemd_service in systemd_services:
+            service_name = systemd_service.replace('vi-', '').replace('.service', '')
+            local_services.append(service_name)
+        return local_services
+    
+    def is_service_enabled(self, service_name: str) -> bool:
+        """Check if a service is enabled on this node"""
+        return service_name in self.get_local_services()
+
+    @property
+    def project_root(self) -> Path:
+        """Get the project root directory"""
+        return Path(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+    
+    @property
+    def data_dir(self) -> Path:
+        """Get the data directory for databases"""
+        data_path = os.getenv('DATA_DIR', str(self.project_root / 'data'))
+        data_dir = Path(data_path)
+        data_dir.mkdir(exist_ok=True, parents=True)
+        return data_dir
+
+
+config = Config()
+
+# Database paths
+SHORT_TERM_DB = config.data_dir / 'memory_active.db'
+LONG_TERM_DB = config.data_dir / 'memory_archive.db'