v0.8.0

v0.8.0: refactor + new features

- Bug fix: SerialState op_lock concurrency race condition
- Bug fix: CSS dead code and undefined variable
- Refactor: split serial_cmd.rs into encoding_utils + multi_string + serial_cmd
- Refactor: split handle_mcp into dedicated handler functions
- Refactor: ChecksumAlgo enum replaces string-based algorithm selection
- Refactor: unified hex parsing, extracted SerialState::to_port_info()
- Rename: McpBuffer -> ReceiveBuffer, window_helper url -> path
- Feature: multi-string items support per-entry name/note
- Feature: LSB/MSB byte-order switch for CRC16/CRC32 checksum