fix: Ensure cover upload directory exists and has proper recursive permissions.

scripts/migrate-covers.mjs

@@ -1,6 +1,6 @@
 import { PrismaClient } from '@prisma/client';
 import { parseBuffer } from 'music-metadata';
-import { readFile, writeFile } from 'fs/promises';
+import { readFile, writeFile, mkdir } from 'fs/promises';
 import path from 'path';
 import { fileURLToPath } from 'url';
 
@@ -38,6 +38,7 @@ async function migrate() {
                     const coverPath = path.join(process.cwd(), 'public/uploads/covers', coverFilename);
 
                     // Ensure directory exists
+                    await mkdir(path.dirname(coverPath), { recursive: true });
                     await writeFile(coverPath, picture.data);
 
                     // Update DB