v1.0.10 - fix temperature bogus fallback

Bug fix: temperature still showing ~63°C after v1.0.9

Investigation: 129 live proxy packets analyzed. Zero `d9` (temp) packets received in this session. Zero unknown tag bytes — every non-BCD byte is a known field tag. The device is simply not sending temperature continuously.

The `d7` values seen (n≈6300–7200 → 63–72°C via n/100) are clearly not temperature — the reference sensor reads ~30°C. `d7` appears to encode a non-temperature measurement on this device (its values track proportionally with `d6` / mins_remaining with a ~3.34× ratio).

Fix: Cap `temp_d7` at 55°C. Values above this threshold are discarded. When no valid temperature source is available (no `d9`, no plausible `d7`), the sensor correctly shows Unavailable instead of a wrong reading.

Devices like the BTG656 that genuinely use `d7` for temperature (reporting 20–45°C) continue to work. `d9` temperature continues to take priority when the device sends it.