Expand aitbc package with new utility modules and enhanced HTTP client

- Add new exception types: RetryError, CircuitBreakerOpenError, RateLimitError
- Enhance AITBCHTTPClient with retry logic, caching, circuit breaker, and rate limiting
- Add AsyncAITBCHTTPClient for async HTTP operations
- Add crypto module with Ethereum key derivation, signing, encryption, and hashing utilities
- Add web3_utils module with Web3Client and create_web3_client
- Add security module with token generation, API key management

cli/enterprise_cli.py

@@ -12,9 +12,10 @@ from pathlib import Path
 from typing import Optional, Dict, Any, List
 import requests
 import getpass
+from aitbc.paths import get_keystore_path
 
 # Default paths
-DEFAULT_KEYSTORE_DIR = Path("/var/lib/aitbc/keystore")
+DEFAULT_KEYSTORE_DIR = get_keystore_path()
 DEFAULT_RPC_URL = "http://localhost:8006"
 
 def get_password(password_arg: str = None, password_file: str = None) -> str: