fix(personal-records): map the new derived metric types to a null PR direction

ANS charge, cardio load, the sleep score, and the body-temperature
deviation reached the MeasurementType enum without a branch in
getPRDirection, which left the exhaustive switch non-total — typecheck
fell through to an implicit undefined return and the drift guard failed.

These are derived / homeostatic composites with no goal axis, so they
join the other scores and temperature metrics on the null PR direction.

src/lib/personal-records/pr-direction.ts

@@ -176,6 +176,16 @@ export function getPRDirection(
     // WALKING_HEART_RATE_AVERAGE case above. Defer to a null PR direction.
     case "AVERAGE_HEART_RATE":
     case "MAX_HEART_RATE":
+    // Derived / homeostatic device composites with no goal axis. ANS
+    // charge, cardio load, and the sleep score are recomputed daily from
+    // their own underlying signals (a PR on them would double-count the
+    // inputs' PRs), and the body-temperature deviation is a baseline-
+    // relative reading where neither direction is an achievement — they
+    // stay null like the other derived scores + temperature metrics above.
+    case "ANS_CHARGE":
+    case "CARDIO_LOAD":
+    case "SLEEP_SCORE":
+    case "BODY_TEMPERATURE_DEVIATION":
       return null;
   }
 }