FM350 temperature fallback
- Read AT+GTSENRDTEMP=1 when AT+ETHERMAL? returns no usable temperature. Convert the modem's soc_max reading from millidegrees Celsius and retain the existing range and jump-confirmation filters. Both FM350 USB profiles share this fallback.
- Reject malformed ETHERMAL readings instead of displaying a fabricated zero that suppresses the fallback. Existing valid ETHERMAL readings remain preferred.
- Capture both temperature commands in diagnostic reports and add the alternative command to the FM350 AT menu.
The fallback follows the FM350 AT manuals and a captured 4PDA response. It reads the modem's SoC temperature and does not change thermal-management or throttling settings.
Validation: 57 regression tests and all 39 FM350 profile scenarios passed. The affected TR3600 modem still requires hardware confirmation; the reason its ETHERMAL query returns no data remains unconfirmed.