v1.2.0- improve handle_unknown messages

[1.2.0] - 2026-05-17

Added

• Decoded the Internet Gateway Status Broadcast (CMD 0x12 from 0x00F0) — payload is {major, minor, embedded_checksum} where the third byte equals major + minor; handle_gateway_status now logs the firmware version and validates the embedded checksum, while firmware-version state population remains with §17. PROTOCOL.md §18 promoted from ⚠️ to ✅, with two confirming samples (5.1 → 05 01 06, 5.0 → 05 00 05) and a note clarifying that byte 13 is the standard frame checksum, not a data field

Changed

• Improved unhandled-message logging in handle_unknown to include the resolved source/destination device names (via addr_info), the CMD byte plus a human-readable name (get_cmd_name table covering 0x05–0xFD; CMDs not in the table render as "Unknown CMD 0xXX"), the declared length byte, and the payload section only — making unknown messages triagable from a single log line without duplicating the raw frame already printed as "RX MSG"

Full Changelog: v1.1.0...v1.2.0