feat(elixir): QR code generate & download function

assets/js/app.js

@@ -40,6 +40,32 @@ window.addEventListener("phx:page-loading-stop", _info => topbar.hide())
 // connect if there are any LiveViews on the page
 liveSocket.connect()
 
+// Add file download functionality
+window.addEventListener("phx:download_file", (event) => {
+  const { filename, data, mime_type } = event.detail
+  
+  // Convert base64 to blob
+  const byteCharacters = atob(data)
+  const byteNumbers = new Array(byteCharacters.length)
+  for (let i = 0; i < byteCharacters.length; i++) {
+    byteNumbers[i] = byteCharacters.charCodeAt(i)
+  }
+  const byteArray = new Uint8Array(byteNumbers)
+  const blob = new Blob([byteArray], { type: mime_type })
+  
+  // Create download link
+  const url = window.URL.createObjectURL(blob)
+  const link = document.createElement('a')
+  link.href = url
+  link.download = filename
+  document.body.appendChild(link)
+  link.click()
+  
+  // Clean up
+  document.body.removeChild(link)
+  window.URL.revokeObjectURL(url)
+})
+
 // expose liveSocket on window for web console debug logs and latency simulation:
 // >> liveSocket.enableDebug()
 // >> liveSocket.enableLatencySim(1000)  // enabled for duration of browser session