Add ASIN support to file organization and metadata

This update enhances audiobook file organization by including the ASIN in folder names and embedding it as a custom metadata tag in audio files (M4B/M4A/MP3). Documentation is updated to reflect the new folder naming convention and metadata tagging. Additionally, local login and registration can now be disabled via an environment variable, and the interactive torrent search modal allows custom search titles for all modes.

src/lib/hooks/useRequests.ts

@@ -216,7 +216,7 @@ export function useInteractiveSearch() {
   const [isLoading, setIsLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
-  const searchTorrents = async (requestId: string) => {
+  const searchTorrents = async (requestId: string, customTitle?: string) => {
     if (!accessToken) {
       throw new Error('Not authenticated');
     }
@@ -227,6 +227,10 @@ export function useInteractiveSearch() {
     try {
       const response = await fetchWithAuth(`/api/requests/${requestId}/interactive-search`, {
         method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+        body: customTitle ? JSON.stringify({ customTitle }) : undefined,
       });
 
       const data = await response.json();