feat(insights): read the persisted wellness scores through the derived contract

Register RECOVERY_SCORE / STRESS_SCORE / STRAIN_SCORE as derived metrics that
read the nightly-persisted COMPUTED Measurement rows — a passthrough, never a
recompute. The dispatcher routes the three ids to a thin reader that returns
the latest score, a trailing-window trend, and a direction-aware band (stress
and strain invert, so a high stress reads red). This lets every surface — the
dashboard, the Coach snapshot, the doctor report — consume the scores through
the one Derived<T> route + hook rather than each growing its own read path.
Regenerate the OpenAPI enum, which picks up the three ids from the registry.

docs/api/openapi.yaml

@@ -2445,6 +2445,9 @@ paths:
               - COINCIDENT_DEVIATION
               - HRV_BALANCE
               - BMI
+              - RECOVERY_SCORE
+              - STRESS_SCORE
+              - STRAIN_SCORE
             description: "Derived-metric id to compute (e.g. VITALS_BASELINE, FITNESS_AGE, VASCULAR_AGE_DELTA, HRV_BALANCE, BMI,
               READINESS). Closed enum: an unknown id 422s. Metrics whose compute has not yet landed return an
               `insufficient` value with reason `not_implemented`."
@@ -7592,6 +7595,9 @@ components:
             - COINCIDENT_DEVIATION
             - HRV_BALANCE
             - BMI
+            - RECOVERY_SCORE
+            - STRESS_SCORE
+            - STRAIN_SCORE
           description: Echoes the requested derived-metric id (tags the union).
         status:
           type: string