Compare glucose signals by the hour and date stale strip readings

The signals of the day held today's newest single reading against the
7- and 30-day mean of every reading. For glucose, whose level climbs
with each meal, a fasting morning read as low against an all-day mean
and fed that into the briefing and status prompts. A type in
SAME_HOURS_TYPES now compares today's mean so far with the earlier
days cut at the local time of today's latest reading, the basis the
coincident-deviation flag and the metric strip already use. Below a
week of like-for-like days there is no signal. The signal carries
basis "sameHours" and both briefing prompts say what it means. Other
metrics keep the reading-against-window comparison.

The usual-range strip called the newest reading today's on every
metric page, even when it was days old. CoachReadBaseline now carries
latestDate (the reading's day in the account's zone) and latestIsToday
(isFromToday), on the REST response and the get_metric_baseline MCP
output. The strip names the date when the reading is not from today,
in all seven locales.

docs/api/openapi.yaml

@@ -59415,7 +59415,16 @@ components:
                   description: Robust upper edge.
                 latest:
                   type: number
-                  description: Today's latest reading, same units.
+                  description: The latest reading, same units. Today's only when `latestIsToday` is true; otherwise it is from
+                    `latestDate`.
+                latestDate:
+                  type: string
+                  pattern: ^\d{4}-\d{2}-\d{2}$
+                  description: Calendar day of the latest reading in the account's time zone, `YYYY-MM-DD`.
+                latestIsToday:
+                  type: boolean
+                  description: True when `latestDate` is today in the account's time zone. When false, a client names the reading's date
+                    instead of calling it today's.
                 placement:
                   type: string
                   enum:
@@ -59438,6 +59447,8 @@ components:
                 - low
                 - high
                 - latest
+                - latestDate
+                - latestIsToday
                 - placement
                 - sampleDays
               additionalProperties: false