Progress Bars II

Requirements

• Initially render no bars and one Add progress bar button. Each click immediately appends one bar at 0%.
• Fill only the earliest incomplete bar over approximately 2000ms using elapsed time; update the view at least every 100ms. Queued bars stay at zero.
• Once a bar reaches 100%, keep it complete and begin the next queued bar. Adding bars during a run must not restart active progress.
• Allow work after the queue becomes idle. Use stable sequential IDs bar-1, bar-2, etc.
• Each bar has role=progressbar, label Progress N, range 0–100 and aria-valuenow matching its fill width. Clear timers on unmount. Basic track and fill styles are supplied.

Examples

Input: Click Add progress bar three times quickly
Output: The first fills for roughly two seconds while the next two remain at zero.

Input: The first completes
Output: It stays full while the second begins filling.