feat: display missing books count badge on series covers

Show an orange badge with BookX icon on series covers when the Stripstream
API reports missing books in the collection. Also display a warning status
badge on the series detail page header.

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

src/components/ui/series-cover.tsx

@@ -1,4 +1,5 @@
 import { ProgressBar } from "./progress-bar";
+import { BookX } from "lucide-react";
 import type { SeriesCoverProps } from "./cover-utils";
 
 export function SeriesCover({
@@ -12,6 +13,7 @@ export function SeriesCover({
   const readBooks = series.booksReadCount;
   const totalBooks = series.bookCount;
   const showProgress = Boolean(showProgressUi && totalBooks > 0 && readBooks > 0 && !isCompleted);
+  const missingCount = series.missingCount;
 
   return (
     <div className="relative w-full h-full">
@@ -27,6 +29,12 @@ export function SeriesCover({
           .filter(Boolean)
           .join(" ")}
       />
+      {showProgressUi && missingCount != null && missingCount > 0 && (
+        <div className="absolute top-1.5 right-1.5 flex items-center gap-0.5 rounded-full bg-orange-500/90 px-1.5 py-0.5 text-white shadow-md backdrop-blur-sm">
+          <BookX className="h-3 w-3" />
+          <span className="text-[10px] font-bold leading-none">{missingCount}</span>
+        </div>
+      )}
       {showProgress ? <ProgressBar progress={readBooks} total={totalBooks} type="series" /> : null}
     </div>
   );