fix(ui): give the neutral score pill a label colour that passes AA

The neutral tone set muted text on the secondary fill, which measures
3.6:1 in the dark theme. The secondary surface's own foreground reads
the same in light and passes in dark.

src/components/ui/__tests__/score-pill.test.tsx

@@ -17,7 +17,7 @@ describe("<ScorePill>", () => {
 
   it("defaults to the neutral tone", () => {
     const html = renderToStaticMarkup(<ScorePill>Low</ScorePill>);
-    expect(html).toContain("bg-secondary text-muted-foreground");
+    expect(html).toContain("bg-secondary text-secondary-foreground");
     expect(html).toContain('data-tone="neutral"');
   });
 

src/components/ui/score-pill.tsx

@@ -30,7 +30,10 @@ const scorePillVariants = cva(
         info: "bg-info/15 text-info",
         warning: "bg-warning/15 text-warning",
         destructive: "bg-destructive/15 text-destructive",
-        neutral: "bg-secondary text-muted-foreground",
+        // The secondary surface's own foreground: muted text on the secondary
+        // fill measured 3.6:1 in the dark theme, under the AA floor a pill
+        // label needs.
+        neutral: "bg-secondary text-secondary-foreground",
       },
       numeric: {
         true: "font-semibold tabular-nums",