Build a progress bar with queued concurrent bars

• A ProgressBar fills from 0 to 100 percent over a configurable duration with a smooth animation (CSS transition or requestAnimationFrame)
• An "Add bar" button appends a new bar to the queue each click
• At most three bars are running at once; the rest wait with an empty bar and start in order as a running bar finishes
• Each bar exposes role="progressbar" with aria-valuenow, aria-valuemin and aria-valuemax
• A finished bar stays full and visually marked as done
• Timers or animations are cleaned up on unmount and no bar restarts on re-render

Only after every requirement works.

• Pause and resume a running bar
• A configurable concurrency limit
• Remove a waiting or running bar, which frees its slot