Bottom nav: flex space-around for proper edge-to-edge distribution

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

sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'ns-v13';
+const CACHE = 'ns-v14';
 const PRECACHE = ['/', 'index.html', 'styles.css', 'app.js', 'sw.js'];
 const SKIP_URLS = ['/rest/stream', '/rest/download', '/config.js'];