feat: add stat card with micro sparkline chart

services/frontend/src/components/dashboard/stat-card.tsx

@@ -0,0 +1,79 @@
+"use client";
+
+import { type LucideIcon } from "lucide-react";
+import { GlassCard } from "@/components/glass/card";
+import { cn } from "@/lib/utils";
+import { Area, AreaChart, ResponsiveContainer } from "recharts";
+
+interface StatCardProps {
+  label: string;
+  value: number | string;
+  icon: LucideIcon;
+  variant?: "default" | "danger" | "success";
+  sparklineData?: { value: number }[];
+  formatter?: (v: number) => string;
+}
+
+export function StatCard({
+  label,
+  value,
+  icon: Icon,
+  variant = "default",
+  sparklineData,
+  formatter = (v) => (typeof v === "number" ? v.toLocaleString() : v),
+}: StatCardProps) {
+  const accentColor = {
+    default: "var(--color-primary)",
+    danger: "var(--color-destructive)",
+    success: "oklch(0.6 0.18 160)",
+  }[variant];
+
+  const bgAccent = {
+    default: "bg-primary/10 text-primary",
+    danger: "bg-destructive/10 text-destructive",
+    success: "bg-emerald-500/10 text-emerald-500",
+  }[variant];
+
+  const numValue = typeof value === "number" ? value : Number(value);
+
+  return (
+    <GlassCard variant="base" className="relative overflow-hidden p-4">
+      <div className="flex items-start justify-between mb-2">
+        <div className={cn("p-1.5 rounded-md", bgAccent)}>
+          <Icon className="size-4" />
+        </div>
+      </div>
+      <div className="text-2xl font-mono font-semibold tracking-tight" style={{ color: accentColor }}>
+        {formatter(numValue)}
+      </div>
+      <div className="text-[11px] text-text-secondary font-medium mt-0.5 tracking-wide uppercase">
+        {label}
+      </div>
+
+      {/* Sparkline background */}
+      {sparklineData && sparklineData.length > 0 && (
+        <div className="absolute bottom-0 left-0 right-0 h-12 opacity-20">
+          <ResponsiveContainer width="100%" height="100%">
+            <AreaChart data={sparklineData}>
+              <defs>
+                <linearGradient id={`spark-grad-${label}`} x1="0" y1="0" x2="0" y2="1">
+                  <stop offset="0%" stopColor={accentColor} stopOpacity={0.5} />
+                  <stop offset="100%" stopColor={accentColor} stopOpacity={0} />
+                </linearGradient>
+              </defs>
+              <Area
+                type="monotone"
+                dataKey="value"
+                stroke={accentColor}
+                strokeWidth={1.5}
+                fill={`url(#spark-grad-${label})`}
+                dot={false}
+                isAnimationActive={false}
+              />
+            </AreaChart>
+          </ResponsiveContainer>
+        </div>
+      )}
+    </GlassCard>
+  );
+}