Delay floppy READ ID completion

Insert a floppy image like [this one](https://github.com/JHRobotics/vmdisp9x/releases/download/v1.2025.0.119/vmdisp9x-1.2025.0.119b-driver-2d.img) in Windows 98 SE. Just clicking the `A:` drive in My Computer causes repeated stalls of ~7.5 seconds.

This happens because [`exec_read_id` raises IRQ6 synchronously](https://github.com/copy/v86/blob/master/src/floppy.js#L756) before Windows has set its interrupt-wait flag. The handler rejects the interrupt, leaving the result unread until the driver times out and resets the controller. This happens with JIT disabled too.

Delaying completion by just 1 ms solves it, but [QEMU uses 20 ms](https://github.com/qemu/qemu/blob/master/hw/block/fdc.c#L1961-L1971).

You can check the [slop86 fix](https://github.com/jlxip/slop86/commit/4ba36fda53cc71b4ff32c582bc75c5c15597f347).

Start in src/floppy.js at exec_read_id, where the issue reports that IRQ6 is raised synchronously before Windows 98 has set its interrupt-wait flag. Compare the timing approaches linked from QEMU and the slop86 fix, then verify that opening the A: drive with the supplied floppy image no longer causes repeated ~7.5-second stalls, including with JIT disabled.

Written by the indexing model from the issue text.