feat(feedback): implement ChipDip-style floating dev feedback & bug report widget with markdown sync

app/static/sw.js

@@ -1,7 +1,7 @@
 // Service Worker for Notes English PWA (Stage 2)
 // Strategy: Cache-first for static assets, Network-first for API calls.
 
-const CACHE_NAME = 'notes-v6.8';
+const CACHE_NAME = 'notes-v6.9';
 const OFFLINE_URL = '/';
 
 const PRECACHE_URLS = [
@@ -22,6 +22,7 @@ const PRECACHE_URLS = [
   '/static/js/modules/reader.js',
   '/static/js/modules/cefr.js',
   '/static/js/modules/grammar.js',
+  '/static/js/modules/feedback.js',
   '/manifest.json',
 ];