v1.15.75

• Mainstream sync (v1.15 backend) - Integrated upstream companion protocol/backend changes for v1.15 without adding new on-device UI screens.
• Default flood scope compatibility - Added persisted default flood scope name/key handling and companion protocol commands for get/set default scope, while keeping scope editing out of the local UI.
• GROUP_DATA binary packets - Added backend send/receive support for channel binary datagrams (CMD_SEND_CHANNEL_DATA / RESP_CODE_CHANNEL_DATA_RECV) so companion apps can use the new group-data protocol.
• Protocol/version update - Bumped companion protocol metadata to firmware protocol code 11 / v1.15.0 and aligned radio frequency validation with upstream lower-frequency support.