Revamp chart colors: replace bland cyan/teal with vibrant blue/indigo/amber palette + fix tooltip indicators

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/charts/diversity-metrics.tsx

@@ -136,7 +136,7 @@ export function DiversityMetricsChart({ data }: DiversityMetricsProps) {
                 data={categoryData}
                 index="category"
                 categories={['Count']}
-                colors={['cyan']}
+                colors={['indigo']}
                 layout="horizontal"
                 yAxisWidth={120}
                 showLegend={false}
@@ -160,7 +160,7 @@ export function DiversityMetricsChart({ data }: DiversityMetricsProps) {
               data={oceanIssueData}
               index="issue"
               categories={['Count']}
-              colors={['teal']}
+              colors={['blue']}
               showLegend={false}
               yAxisWidth={40}
               className="h-[400px]"