refactor(telemetry): text-only list empty states, distinct p50/p95 series

- paginated-list empty prop is a plain string, no icon block
- second sparkline series drawn in dimmed color; area disabled on dual charts
- duration legend shows latest p50/p95 values

src/features/telemetry/components/usage-screen.tsx

@@ -77,6 +77,8 @@ const FnDurationDetail = ({ fn, from, to }: { fn: string; from: string; to: stri
   const days = listDays({ from, to });
   const p50 = fillDailySeries(rows, "server_fn.duration.p50", fn, days);
   const p95 = fillDailySeries(rows, "server_fn.duration.p95", fn, days);
+  const lastNonZero = (series: number[]) =>
+    [...series].reverse().find((value) => value > 0) ?? 0;
 
   return (
     <Stack gap="xs">
@@ -84,7 +86,6 @@ const FnDurationDetail = ({ fn, from, to }: { fn: string; from: string; to: stri
         data={p50}
         series2={p95}
         height={64}
-        showArea
         scale={{
           start: dayLabel(i18n, from),
           end: dayLabel(i18n, to),
@@ -97,7 +98,7 @@ const FnDurationDetail = ({ fn, from, to }: { fn: string; from: string; to: stri
             <line x1={0} y1={4} x2={18} y2={4} stroke="var(--mantine-color-anchor)" strokeWidth={2} />
           </svg>
           <Text size="xs" c="dimmed">
-            <Trans>p50</Trans>
+            <Trans>p50</Trans> · {Math.round(lastNonZero(p50))}ms
           </Text>
         </Group>
         <Group gap={6}>
@@ -107,13 +108,13 @@ const FnDurationDetail = ({ fn, from, to }: { fn: string; from: string; to: stri
               y1={4}
               x2={18}
               y2={4}
-              stroke="var(--mantine-color-anchor)"
+              stroke="var(--mantine-color-dimmed)"
               strokeWidth={2}
               strokeDasharray="4 3"
             />
           </svg>
           <Text size="xs" c="dimmed">
-            <Trans>p95</Trans>
+            <Trans>p95</Trans> · {Math.round(lastNonZero(p95))}ms
           </Text>
         </Group>
       </Group>