This commit introduces the security_tier parameter to all SecureChatCompletion calls, allowing users to specify security levels (standard, high, maximum). It also refactors secure memory management in SecureCompletionClient.py to use secure_bytearray instead of secure_bytes, improves memory protection by aligning addresses to page boundaries, and enhances the secure memory locking mechanism. The README.md has been updated to document the new security_tier parameter and include missing import statements.
