This commit adds common units tests and CI sanitasion.
Additional context for commit b64d9c4498:
- Fixed macOS/Linux non-portable and unsafe shell usage by adding a posix_spawn helper and replacing system() calls in virtual_interface.cpp.
- Fixed SessionRegistry::erase() to remove mIPSessions and mSessionIPs entries in session_registry.cpp.
- Prevented message-length truncation in tcp_message_handler.cpp by rejecting payloads > 65535 bytes.
- Validated handshake message sizes and removed silent truncation in:
- tcp_connection.cpp
- tcp_client.cpp
- Canonicalized and validated config and whitelist paths in utils.cpp using std::filesystem.
- Hardened environment-provided config path handling in main.cpp.
- Validated UDP ciphertext lengths and fixed session ID endianness in udp_client.cpp.
- Scheduled periodic SessionRegistry::cleanupExpired() in main.cpp (every 5 minutes).
