feat(syntonia): Baofeng UV-5R serial protocol implementation #79
Description
From Phase 02 PLAN.md, REQ-01 + REQ-02 + REQ-03.
Baofeng radio programming protocol:
- 9600 baud serial communication
- 7-byte handshake sequence
- 64-byte read / 16-byte write operations
- Calibration EEPROM safety: forbidden address ranges hardcoded to prevent bricking
- Cross-radio detection via handshake response
BF-F8HP variant handling (REQ-02):
- Tri-power level support
- Magic bytes:
50 BB FF 20 14 04 13 - Dropped-byte workaround at address 0x1FCF
- Aux block warm-up sequence
UV-5RM Plus (REQ-03): identify and treat as BF-F8HP variant (UV-5R family).
Groups REQ-01, REQ-02, REQ-03 as they're all part of the Baofeng protocol family.