fix(insights): cut glucose days at today's latest reading and say so

The same-hours comparison cut the earlier days at the current clock time.
At two in the afternoon a day holding only its fasting reading was then
held against mornings plus lunch, and read as below its range again. The
earlier days are now cut at the local time of today's latest reading.

A range read this way is the usual range for this time of day, not the
whole-day band other surfaces show. The deviation carries a basis, the
health-status API publishes it as `basis` (`day` or `sameHours`), and the
Today lead and the health-status card name the range as the one for this
time of day, in all seven locales.

docs/api/openapi.yaml

@@ -60433,6 +60433,14 @@ components:
                 enum:
                   - above
                   - below
+              basis:
+                type: string
+                enum:
+                  - day
+                  - sameHours
+                description: "What `low`/`high` describe: the usual whole day (`day`), or the usual range for this time of day
+                  (`sameHours`), used for a day still in progress whose mean moves with the hour (glucose). Additive
+                  since v1.40.3."
             required:
               - type
               - value
@@ -60440,6 +60448,7 @@ components:
               - low
               - high
               - direction
+              - basis
             additionalProperties: false
         shifts:
           type: array