feat(charts): put the drawn data points under the chart as a table

A chart shows the shape and hides the numbers. An appointment needs the
numbers, and so does anyone moving readings into a spreadsheet.

The table reads the same expression the chart hands Recharts, after the range
slice, the week/month bucketing and the display scale, and it formats through
the chart's own value and date formatters. Nothing is re-derived, so a cell and
the tooltip cannot print two numbers for one point.

Collapsed by default, with the point count in the trigger so the size reads
while it is closed; the region scrolls in its own box rather than growing the
page, and the table primitive already scrolls a wide row set sideways. The
caption names the grain, because a weekly mean labelled as a daily reading
would be a lie, and the grain now has one source shared with the bucketing.
Derived overlays get no column: a moving average is drawn from the points, not
measured. An empty window renders no table at all, since the chart's own empty
state already says there is nothing there.

Opt-in per mount. The metric sub-pages take it; the dashboard tiles do not,
because a table under every tile buries the dashboard it summarises.

Refs #636

src/app/insights/blood-pressure/page.tsx

@@ -173,6 +173,7 @@ export default function InsightsBlutdruckPage() {
         compareBaseline={compareBaseline}
         userTimezone={user?.timezone}
         onVisibleStats={onVisibleStats}
+        showDataTable
       />
 
       {/* v1.12.4 — target card sits between the chart and the assessment on

src/app/insights/bmi/page.tsx

@@ -123,6 +123,7 @@ export default function InsightsBmiPage() {
         valueBands={BMI_BANDS}
         compareBaseline={compareBaseline}
         userTimezone={user?.timezone}
+        showDataTable
       />
 
       <MetricTargetSummary slug="bmi" />

src/app/insights/pulse/page.tsx

@@ -158,6 +158,7 @@ export default function InsightsPulsPage() {
         compareBaseline={compareBaseline}
         userTimezone={user?.timezone}
         onVisibleStats={onVisibleStats}
+        showDataTable
       />
 
       {/* S11 — the intraday "shape of the day" layer: 10-minute mean heart

src/app/insights/weight/page.tsx

@@ -162,6 +162,7 @@ export default function InsightsGewichtPage() {
         userTimezone={user?.timezone}
         valueScale={weightScale}
         onVisibleStats={onVisibleStats}
+        showDataTable
       />
 
       <MetricTargetSummary slug="weight" />