feat: Introduce dashboard, my courses, and browse pages for learner course discovery and management.

Frontend-Learner/pages/browse/index.vue

@@ -130,12 +130,9 @@ const filteredCourses = computed(() => {
               @error="(e) => (e.target as HTMLImageElement).style.display = 'none'" 
             />
             <div 
-              v-else-if="!course.thumbnail_url || true" 
+              v-else 
               class="absolute inset-0 flex items-center justify-center bg-gradient-to-br from-slate-800 to-slate-900"
             >
-               <div class="w-20 h-20 rounded-2xl bg-white/5 flex items-center justify-center text-5xl group-hover:scale-110 transition-transform duration-500 shadow-inner border border-white/5">
-                 📚
-               </div>
             </div>
             <!-- Level Badge (Neutral/Warning/Success variants) - Optional based on data -->
              <div v-if="course.levelType" class="absolute top-4 right-4">