fix: send correct number of sequences for wheel scroll in alt buffer

[dolonet]

Fixes #5194

Problem

When the terminal is in the alt buffer (no scrollback — vim, less, man, etc.), mouse wheel events are converted to up/down arrow key sequences. Previously only a single sequence was sent per wheel event, regardless of how many lines the wheel reported scrolling. This made scrolling in alternate-screen apps feel sluggish — one notch of the wheel moved exactly one line instead of the expected three.

The same code path that handles touch scroll (_handleTouchScrollAsKeys) already sends one sequence per line correctly. The wheel path was inconsistent with it.

Fix

Loop lines times when sending the sequence, matching the existing touch scroll logic:

// before
this._coreService.triggerDataEvent(sequence, true);

// after
for (let i = 0; i < lines; i++) {
  this._coreService.triggerDataEvent(sequence, true);
}

lines is already computed by _consumeWheelEvent just above — no new state needed.

Testing

Manually verified with less and man: one scroll click now moves the expected number of lines. The touch scroll path is unchanged.