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

app/static/js/app.js

@@ -11,6 +11,7 @@ import { initReader, loadBookshelf, openBook } from './modules/reader.js';
 import { initCefr, loadCefrOverview, startCefrQuiz } from './modules/cefr.js';
 import { initGrammar, loadGrammarUnits, openGrammarUnit } from './modules/grammar.js';
 import { initLessonModule, openLessonConfigurator } from './modules/lesson.js';
+import { initFeedbackWidget } from './modules/feedback.js';
 
 let currentUser = null;
 let isRouting = false;
@@ -686,6 +687,7 @@ document.addEventListener('DOMContentLoaded', () => {
     initCefr();
     initGrammar();
     initLessonModule();
+    initFeedbackWidget();
 
     // 5. Global Navigation & Header Actions
     const navBrandHome = document.getElementById('nav-brand-home');