fix(workouts): hold training load through unscored days

A day without a stored training impulse was read as a rest day, so a
watch left off or a nightly run that had not happened yet pulled
fitness and fatigue toward zero. Such a day is now not rated: the
averages hold through it, the series marks it, and the card says how
many of the last 42 days were rated. A scored day of 0 stays rest. The
figures describe the last stored day rather than always yesterday.

docs/api/openapi.yaml

@@ -49454,7 +49454,8 @@ components:
               const: ok
             asOf:
               type: string
-              description: The last scored UTC day the figures describe.
+              description: "The last UTC day with a stored impulse, at most yesterday: a nightly run that has not happened yet never
+                reads as a rest day."
             ctl:
               type: number
               description: "Fitness: 42-day exponentially weighted TRIMP."
@@ -49472,6 +49473,15 @@ components:
               type: integer
               minimum: -9007199254740991
               maximum: 9007199254740991
+            recentRatedDays:
+              type: integer
+              minimum: -9007199254740991
+              maximum: 9007199254740991
+              description: Days of the trailing `recentDays` (42, or fewer when covered less) with a stored impulse.
+            recentDays:
+              type: integer
+              minimum: -9007199254740991
+              maximum: 9007199254740991
             warmingUp:
               type: boolean
               description: "True below 42 covered days: both averages start at zero."
@@ -49488,11 +49498,16 @@ components:
                     type: number
                   tsb:
                     type: number
+                  rated:
+                    type: boolean
+                    description: "False for a day without a stored impulse (never scored): the averages held through it rather than counting
+                      it as rest."
                 required:
                   - day
                   - ctl
                   - atl
                   - tsb
+                  - rated
                 additionalProperties: false
               description: The trailing 90 days, oldest first; `tsb` is form going into the day.
           required:
@@ -49503,6 +49518,8 @@ components:
             - tsb
             - daysCovered
             - trainingDays
+            - recentRatedDays
+            - recentDays
             - warmingUp
             - series
           additionalProperties: false
@@ -49530,9 +49547,9 @@ components:
             - daysCovered
             - trainingDays
           additionalProperties: false
-      description: "v1.44 — the fitness-fatigue model over the stored daily heart-rate training impulse (Banister TRIMP; a day
-        without a stored impulse counts as rest). Needs 28 days and three training days. TRIMP units: comparable with
-        the person's own past only."
+      description: "v1.44 — the fitness-fatigue model over the stored daily heart-rate training impulse (Banister TRIMP; a
+        scored day without training is 0, a day without a stored impulse is not rated and the averages hold through it).
+        Needs 28 days and three training days. TRIMP units: comparable with the person's own past only."
     GetWorkoutResponse:
       type: object
       properties: