Progress Bars III

Requirements

• Each Add progress bar click appends a new zero-percent bar with a stable sequential ID. Start with an empty list.
• At most three bars may be running at any time. Admit queued bars in insertion order whenever a slot opens. All active bars progress concurrently and independently.
• Each bar takes approximately 2000ms of active elapsed time to finish. Use timestamps and update at least every 100ms. Adding work must not restart older bars.
• Preserve completed bars at 100%. Allow new work after the queue becomes idle. Expose data-status queued/running/done, role=progressbar, Progress N labels, range 0–100 and synchronized aria-valuenow/fill width.
• Clear timers on unmount. Basic track styles and all controls are supplied.

Examples

Input: Add five bars quickly
Output: Three run concurrently; two wait at zero.

Input: An active bar completes
Output: The earliest queued bar takes its slot.