Fix #241: Remove progress bar animation

[jloutsch]

Summary

This PR addresses issue #241 by removing the animation transition on the LinearProgress component during file transfers. Previously, the progress bar would smoothly animate back to 0% when starting the next file, creating a confusing "rubber band" effect.

Changes

• Added new CSS class linearProgress to disable Material-UI's default transition animation
• Applied the className to the LinearProgress component in the ProgressBar dialog

Files Modified:

• app/components/DialogBox/styles/ProgressBar.js - Added CSS to disable transition
• app/components/DialogBox/components/ProgressBar.jsx - Applied className to component

Testing

• Tested with Android device file transfer
• Verified progress bar now jumps instantly to 0% when starting next file instead of animating
• No visual "bounce back" effect during multi-file transfers

Impact

Small but noticeable UX improvement - progress bar now accurately reflects the current file transfer status without confusing animation delays.

Closes #241