Improve FTP upload progress and widen print modal

FTP upload: reduce chunk size from 1MB to 64KB for smooth progress bar
  updates (~1s intervals instead of 20+ second gaps). Skip voidresp() for
  all printer models — H2D delays the 226 response by 30+ seconds after
  data transfer, causing a hang at 100%. Add transfer speed and TLS
  handshake timing to logs for diagnosing slow connections.

  Print/Schedule modal: widen from max-w-lg (512px) to max-w-2xl (672px)
  to accommodate long filament profile names like "PLA Support for PETG
  PETG Basic @Bambu Lab H2D 0.4 nozzle".

frontend/src/components/PrintModal/index.tsx

@@ -657,7 +657,7 @@ export function PrintModal({
       onClick={isSubmitting ? undefined : onClose}
     >
       <Card
-        className="w-full max-w-lg max-h-[90vh] overflow-y-auto"
+        className="w-full max-w-2xl max-h-[90vh] overflow-y-auto"
         onClick={(e) => e.stopPropagation()}
       >
         <CardContent className={mode === 'reprint' ? '' : 'p-0'}>