feat(stats): add v1 immersion stats dashboard (#19)

stats/src/components/anime/CollapsibleSection.tsx

@@ -0,0 +1,38 @@
+import { useId, useState } from 'react';
+
+interface CollapsibleSectionProps {
+  title: string;
+  defaultOpen?: boolean;
+  children: React.ReactNode;
+}
+
+export function CollapsibleSection({
+  title,
+  defaultOpen = true,
+  children,
+}: CollapsibleSectionProps) {
+  const [open, setOpen] = useState(defaultOpen);
+  const contentId = useId();
+
+  return (
+    <div className="bg-ctp-surface0 border border-ctp-surface1 rounded-lg">
+      <button
+        type="button"
+        onClick={() => setOpen(!open)}
+        aria-expanded={open}
+        aria-controls={contentId}
+        className="w-full flex items-center justify-between p-4 text-left"
+      >
+        <h3 className="text-sm font-semibold text-ctp-text">{title}</h3>
+        <span className="text-ctp-overlay2 text-xs" aria-hidden="true">
+          {open ? '▲' : '▼'}
+        </span>
+      </button>
+      {open && (
+        <div id={contentId} className="px-4 pb-4">
+          {children}
+        </div>
+      )}
+    </div>
+  );
+}