Skin Temp reads as a delta on Today and in the detail screen, not a temperature #1844

The Today "Skin Temp" card and the Skin Temp detail screen still lead with the deviation (0.0 Δ°C), so a reading that should be a temperature shows as a delta against a baseline the screen never names.

The Health tile already solved this. #1663 stored the nightly ABSOLUTE beside the deviation (dailyMetric.skinTempC), and #1665 made the Health tile lead with it, demoting the delta to a note underneath. The rationale in skinTempLeadsWithAbsolute still stands:

A deviation with no anchor cannot be read — "+0.9" is a fever or a warm bedroom and nothing on the tile says which — so the absolute leads and the deviation becomes the context beneath it.

Three surfaces never came onto that pattern and still read skinTempDevC only:

• TodayScreen DashboardCard.SKIN_TEMP — the "Your Cards" row
• TodayScreen KeyMetric.SKIN_TEMP — the Key Metrics tile
• HealthScreen skin-temp detail — title, unit, LATEST, min/avg/max and every readings row, all keyed off SkinTempDisplay.kind(latest) on the deviation series

Plus the Apple twins of each.

Δ°C itself is not the defect and should stay wherever a deviation is genuinely what is shown (#622 added it so −0.1 °C is not read as a broken thermometer). The defect is leading with a deviation when the night measured a real temperature.

Second case the same change picks up

A CALIBRATING night is the reverse of the common one: recomputeSkinTempDev returns null until the baseline is usable (~4 nights), while the absolute is measured from night one. Those wearers currently see the empty state on Today with a real temperature already sitting behind it, which is the same thing #1665 fixed on Health.

Note for anyone testing this

skinTempC is nullable and additive — it landed 2026-08-27 and refills on the next scoring pass, re-derived from the raw skinTempSample rows still on disk. Nights scored before that date keep the deviation-led display until a rescore, so on an install whose newest reading predates 27 Aug this change is correctly invisible until then.