feat: Implement TaskFlow logos and icons throughout the application

- Add favicon files (16x16 to 256x256, .ico)
- Add PWA icons (128, 256, 512, 1024)
- Add apple-touch-icon for iOS
- Add transparent icons for loading screens
- Add horizontal logo with tagline for auth page
- Update HTML head with proper favicon links
- Update PWA manifest with correct icon references
- Update sidebar header with branded icon
- Update mobile header with branded icon
- Update auth/login pages with logo display
- Update loading state with branded splash screen
- Update 404 page with logo header
- Update email template to use proper logo URL
- Update service worker and push notifications to use correct icons

server/push.ts

@@ -207,8 +207,8 @@ export async function sendPushNotification(
   const notificationPayload = JSON.stringify({
     title: payload.title,
     body: payload.body,
-    icon: payload.icon || '/favicon.png',
-    badge: payload.badge || '/favicon.png',
+    icon: payload.icon || '/icon-256.png',
+    badge: payload.badge || '/icon-128.png',
     tag: payload.tag || `taskflow-${Date.now()}`,
     data: payload.data || {}
   });