Add hideAvailable filter and unified pagination

Add support for hiding audiobooks that are already available by introducing a hideAvailable query flag and excluding matching ASINs at the DB level. Implemented getAvailableAsins() in audiobook-matcher to gather ASINs from the library and completed requests, and wired it into the popular and new-releases API routes to apply a notIn filter. Propagated the hideAvailable flag through useAudiobooks so client requests include the parameter, and adjusted the homepage to reset pagination when the flag changes. Replaced two StickyPagination instances with a new UnifiedPagination component (new file) that provides a single context-aware floating paginator which tracks the dominant section and allows switching between Popular and New Releases. Also removed client-side filtering in favor of server-side exclusion and made small imports/cleanup in page.tsx.

src/lib/utils/audiobook-matcher.ts

@@ -272,6 +272,44 @@ export async function enrichAudiobooksWithMatches(
   return results;
 }
 
+/**
+ * Get all ASINs that are considered "available" — present in library or have completed requests.
+ * Used by paginated API routes to exclude available items at the DB level.
+ */
+export async function getAvailableAsins(): Promise<Set<string>> {
+  const [libraryItems, completedRequests] = await Promise.all([
+    // ASINs present in the library (Plex or Audiobookshelf)
+    prisma.plexLibrary.findMany({
+      where: { asin: { not: null } },
+      select: { asin: true },
+      distinct: ['asin'],
+    }),
+    // ASINs with completed audiobook requests
+    prisma.audiobook.findMany({
+      where: {
+        audibleAsin: { not: null },
+        requests: {
+          some: {
+            status: 'completed',
+            type: 'audiobook',
+            deletedAt: null,
+          },
+        },
+      },
+      select: { audibleAsin: true },
+    }),
+  ]);
+
+  const asins = new Set<string>();
+  for (const item of libraryItems) {
+    if (item.asin) asins.add(item.asin);
+  }
+  for (const item of completedRequests) {
+    if (item.audibleAsin) asins.add(item.audibleAsin);
+  }
+  return asins;
+}
+
 /**
  * Normalize ISBN for comparison (remove dashes and spaces)
  */