spa: restore metrics on dashboard; it was the only route to the metrics page

hiding the card when nothing was recorded made /metrics unreachable, so an
account with no readings could never enter its first one. always shown now,
with today's readings or a prompt. second entry point on stats.

also: metric inputs had no label association, so all eight announced as
'Not recorded' (the placeholder). minutes read as 7h 12m, not 432.

spa/tests/components/metric-value.test.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it } from "vitest"
+import { METRIC_FIELDS } from "@/components/metric/metric-fields"
+import { formatMetric } from "@/components/metric/metric-value"
+
+const field = (kind: string) =>
+  METRIC_FIELDS.find((each) => each.kind === kind)!
+
+describe("reading a metric back", () => {
+  it("reads minutes as hours and minutes", () => {
+    expect(formatMetric(field("sleepMinutes"), 432)).toBe("7h 12m")
+  })
+
+  it("drops the hours when there are none", () => {
+    expect(formatMetric(field("exerciseMinutes"), 45)).toBe("45m")
+  })
+
+  it("drops the minutes when the hour is whole", () => {
+    expect(formatMetric(field("sleepMinutes"), 480)).toBe("8h")
+  })
+
+  it("shows zero minutes as zero, not blank", () => {
+    expect(formatMetric(field("awakeMinutes"), 0)).toBe("0m")
+  })
+
+  it("leaves counts alone but groups them", () => {
+    expect(formatMetric(field("steps"), 8432)).toBe((8432).toLocaleString())
+    expect(formatMetric(field("restingHeartRate"), 58)).toBe("58")
+  })
+})