feat(glucose): read glucose in one unit across series, CSV, and detail page

Glucose is stored canonical mg/dL but the series DTO, CSV export, and detail
page emitted raw mg/dL while FHIR already converted to the user preference.

Convert at serialization through the single convertGlucose helper:
- series route sets unit from the user's glucoseUnit and converts each point
- CSV export converts BLOOD_GLUCOSE rows and emits the unit in the unit column
- the detail page + stat strip honour the preference via the chart value scale
- declare the trailing-90-day window in the glucose median label across locales

mmol/L-preference users now see the blood-glucose page, stat strip, iOS series,
and CSV in mmol/L; mg/dL users are unchanged.

src/components/insights/__tests__/metric-stat-strip.test.tsx

@@ -70,6 +70,37 @@ describe("<MetricStatStrip>", () => {
     expect(html).toBe("");
   });
 
+  it("renders the default 'Median' label when no override is given", () => {
+    const html = render(<MetricStatStrip summary={populated} unit="bpm" />);
+    expect(html).toContain("Median");
+  });
+
+  // v1.16.16 — glucose declares the trailing-90-day p50 window in the label
+  // so the median is not read as an all-time central value.
+  it("renders an overridden median label when medianLabel is provided", () => {
+    const html = render(
+      <MetricStatStrip
+        summary={populated}
+        unit="mg/dL"
+        medianLabel="Median glucose (90 days)"
+      />,
+    );
+    expect(html).toContain("Median glucose (90 days)");
+  });
+
+  it("honours fractionDigits for integer-unit metrics (0 decimals)", () => {
+    const html = render(
+      <MetricStatStrip
+        summary={{ ...populated, min: 100, max: 180, median: 126 }}
+        unit="mg/dL"
+        fractionDigits={0}
+      />,
+    );
+    // No "100.0" — integer precision.
+    expect(html).toContain("100 mg/dL");
+    expect(html).not.toContain("100.0");
+  });
+
   it("falls back to mean when median is absent (older payload)", () => {
     const noMedian: DataSummary = { ...populated, median: null };
     const html = render(<MetricStatStrip summary={noMedian} unit="bpm" />);

src/components/insights/healthkit-metric-page.tsx

@@ -142,6 +142,18 @@ export interface HealthKitMetricPageProps {
    * "no trend to project yet" state rather than a line.
    */
   forecast?: boolean;
+  /**
+   * v1.16.16 — decimal precision for the stat-strip values. Defaults to the
+   * strip's own default (1). Blood glucose passes 0 for mg/dL (integer
+   * readings) and 1 for mmol/L so the numbers and the unit agree.
+   */
+  statFractionDigits?: number;
+  /**
+   * v1.16.16 — optional override for the stat strip's "Median" label. Blood
+   * glucose passes a window- + context-declaring string so the trailing
+   * 90-day p50 is not read as an all-time central value.
+   */
+  statMedianLabel?: string;
 }
 
 export function HealthKitMetricPage({
@@ -162,6 +174,8 @@ export function HealthKitMetricPage({
   statusMetric,
   statIcon,
   forecast = false,
+  statFractionDigits,
+  statMedianLabel,
 }: HealthKitMetricPageProps) {
   const { user, isAuthenticated } = useAuth();
   const { t } = useTranslations();
@@ -289,9 +303,11 @@ export function HealthKitMetricPage({
         <MetricStatStrip
           summary={summary}
           unit={yAxisUnit ?? unit}
+          fractionDigits={statFractionDigits}
           seriesLabel={title}
           icon={statIcon}
           windowStats={statsByType?.[measurementType] ?? null}
+          medianLabel={statMedianLabel}
         />
       }
       diversityNudge={

src/components/insights/metric-stat-strip.tsx

@@ -92,6 +92,15 @@ export interface MetricStatSeries {
    * single-series mode omits it.
    */
   dataKey?: string;
+  /**
+   * v1.16.16 — optional override for the "Median" cell label. The strip's
+   * median is a trailing-90-day p50 (see `DataSummary.median` /
+   * `summaries-slice.ts`); the default generic "Median" label leaves that
+   * window undeclared. Blood glucose passes a window- + context-declaring
+   * string (e.g. "Median glucose (90 days)") so the number is not read as an
+   * all-time central value. Omit it to keep the generic label.
+   */
+  medianLabel?: string;
 }
 
 type MetricStatStripProps = Partial<MetricStatSeries> & {
@@ -129,6 +138,7 @@ function SeriesBlock({
   icon,
   windowStats,
   dataKey,
+  medianLabel,
 }: MetricStatSeries) {
   const { t } = useTranslations();
   const fmt = useFormatters();
@@ -154,7 +164,7 @@ function SeriesBlock({
     { key: "max", label: t("insights.subPage.stats.max"), value: source.max },
     {
       key: "median",
-      label: t("insights.subPage.stats.median"),
+      label: medianLabel ?? t("insights.subPage.stats.median"),
       value: source.median,
     },
     {
@@ -203,6 +213,7 @@ export function MetricStatStrip({
   icon,
   windowStats,
   dataKey,
+  medianLabel,
   series,
   groupLabel,
 }: MetricStatStripProps) {
@@ -264,6 +275,7 @@ export function MetricStatStrip({
           icon={icon}
           windowStats={windowStats}
           dataKey={dataKey}
+          medianLabel={medianLabel}
         />
       </CardContent>
     </Card>