Fix: Improve API rate limit handling during CSV import

- Update 'fetchWithRetry' in api.js to respect Retry-After header and use exponential backoff for 429 errors.
- Add 300ms delay between requests in CSV import loop to reduce load.

js/api.js

@@ -48,7 +48,19 @@ export class LosslessAPI {
                     const response = await fetch(url, { signal: options.signal });
 
                     if (response.status === 429) {
-                        throw new Error(RATE_LIMIT_ERROR_MESSAGE);
+                         const retryAfter = response.headers.get('Retry-After');
+                         let waitTime = 2000 * attempt; // Default exponential backoff
+
+                         if (retryAfter) {
+                             const seconds = parseInt(retryAfter, 10);
+                             if (!isNaN(seconds)) {
+                                 waitTime = seconds * 1000;
+                             }
+                         }
+                         
+                         console.warn(`Rate limit hit. Waiting ${waitTime}ms before retry ${attempt}/${maxRetries}...`);
+                         await delay(waitTime);
+                         continue;
                     }
 
                     if (response.ok) {

js/app.js

@@ -1058,6 +1058,9 @@ async function parseCSV(csvText, api, onProgress) {
 
             // Search for the track in hifi tidal api's catalog
             if (trackTitle && artistNames) {
+                // Add a small delay to prevent rate limiting
+                await new Promise(resolve => setTimeout(resolve, 300));
+                
                 try {
                     const searchQuery = `${trackTitle} ${artistNames}`;
                     const searchResults = await api.searchTracks(searchQuery);