feat: add storage management and utility functions

- Implement storage service for file management
- Add support for external and system storage backends
- Include utility functions for environment variables
- Add hash utilities for secure operations
- Implement validation utilities for data integrity
- Support file encryption and secure storage
- Add proper error handling and logging for storage operations

storage/storage.go

@@ -0,0 +1,6 @@
+package storage
+
+type Storage interface {
+	GetCertificate(key string) (interface{}, error)
+	GetPrivateKey(key string) (interface{}, error)
+}