feat(insights): elevate coincident-deviation to a dedicated "Today's signal" card

Promote the COINCIDENT_DEVIATION flag from a fire-only tile buried in the
below-the-fold vitals grid to an always-mounted headline card at the top of
the Insights overview. The card renders four calm states off the single
existing derived payload — building-baselines, all-clear, watch, fired — with
no new engine math, route, or schema change.

Keep it calm and clinically safe: at most an amber band, never red, no score,
no chart, no push. Soften a fired flag to the watch tone when the backing
history is thin. The fired/watch states carry the load-bearing "possible
factors, never a cause / not a diagnosis" framing and reuse ProvenanceExplainer
+ CoverageMeter + the band tokens verbatim.

Remove the now-redundant tile, its batch token, and the hasRenderableVital
branch from the vitals grid so the signal is not shown twice.

src/app/insights/page.tsx

@@ -97,6 +97,24 @@ const RhythmEventsCard = dynamic(
     })),
   { ssr: false },
 );
+// v1.10.3 — "Today's signal" headline card. Promotes COINCIDENT_DEVIATION from
+// a buried below-the-fold tile to the top-of-overview daily read (the
+// always-present Apple/WHOOP/Oura pattern). Deferred behind `next/dynamic`; it
+// owns its own derived-metric query and renders four calm states. A
+// fixed-height skeleton matches the resolved card so the top of the page does
+// not shift while the chunk + data resolve.
+const CoincidentDeviationCard = dynamic(
+  () =>
+    import("@/components/insights/coincident-deviation-card").then((mod) => ({
+      default: mod.CoincidentDeviationCard,
+    })),
+  {
+    ssr: false,
+    loading: () => (
+      <div className="bg-card border-border h-[7.5rem] animate-pulse rounded-xl border motion-reduce:animate-none" />
+    ),
+  },
+);
 
 /**
  * v1.4.25 W4d — Insights mother page.
@@ -246,6 +264,8 @@ export default function InsightsPage() {
         healthScore={analytics?.healthScore ?? undefined}
       />
 
+      <CoincidentDeviationCard enabled={isAuthenticated} />
+
       <div className="flex justify-end">
         <Button
           size="sm"