release(v1.8.2): media progress tracking + watched badges; PWA scaffolding; mobile switcher (closes #37)

public/js/pwa/sw.js

@@ -0,0 +1,9 @@
+// public/js/pwa/sw.js
+const SW_VERSION = '{{APP_QVER}}';
+const STATIC_CACHE = `fr-static-${SW_VERSION}`;
+const STATIC_ASSETS = [
+  '/', '/index.html',
+  '/css/styles.css?v={{APP_QVER}}',
+  '/js/main.js?v={{APP_QVER}}',
+  '/assets/logo.svg?v={{APP_QVER}}'
+];