- Change net.Listen("unix") to net.ListenUnixgram("unixgram")
- Replace connection-based Accept() with ReadFromUnix() datagram reading
- Remove connection limiting semaphore (not needed for DGRAM)
- Update tests with datagram-specific tests
- Socket permissions default to 0666 (world read/write)
Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>