fix: playlist cover upload via PUT /api/playlist/{id} with base64 imageData

Navidrome (react-admin) expects image as base64 data URL in JSON body,
not as a raw binary POST to /image endpoint. Bump SW to ns-v35.

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

sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'ns-v34';
+const CACHE = 'ns-v35';
 const PRECACHE = ['/', 'index.html', 'styles.css', 'app.js', 'manifest.json', 'icon.svg'];
 const SKIP_PATHS = ['/rest/stream', '/rest/download', '/config.js'];