Enhance audio and visual elements in the UI for improved user experience

- Added a new script in package.json to generate welcome speech audio for enhanced onboarding.
- Updated SplashScreen.vue and OnboardingWrapper.vue to use the new intro background image and poster.
- Modified Dashboard.vue and Login.vue to reflect changes in background images for consistency.
- Removed outdated background images and updated references to ensure a cohesive visual theme.
- Improved tap-to-start feature with new text and logo in SplashScreen.vue for better engagement.
- Enhanced audio playback functionality in useLoginSounds.ts to include welcome speech.

neode-ui/src/views/Dashboard.vue

@@ -341,7 +341,7 @@ const currentBackgroundImage = computed(() => {
   if (showAppStoreBackground.value) return 'bg-appstore.jpg'
   if (showCloudBackground.value) return 'bg-cloud.jpg'
   if (showHomeBackground.value) return 'bg-home.jpg'
-  return 'bg-4.jpg'
+  return 'bg-intro.jpg'
 })
 
 const altBackgroundImage = computed(() => {
@@ -352,7 +352,7 @@ const altBackgroundImage = computed(() => {
   if (showAppStoreBackground.value) return 'bg-appstore.jpg'
   if (showCloudBackground.value) return 'bg-cloud.jpg'
   if (showHomeBackground.value) return 'bg-home.jpg'
-  return 'bg-3.jpg'
+  return 'bg-intro-3.jpg'
 })
 
 // Check if overlay should be dark (0.8 opacity)
@@ -1442,7 +1442,7 @@ aside:not(.sidebar-animate) .sidebar-logout-btn {
   will-change: transform, opacity;
 }
 
-/* Default state - bg-4 visible, bg-3 hidden back */
+/* Default state - bg-intro visible, bg-intro-3 hidden back */
 .dashboard-view .bg-layer:first-of-type {
   opacity: 1;
   transform: translateZ(0) scale(1);