[Feature request] Adjust the height of the preview window automatically

- [x] I have read through the manual page (`man fzf`)
- [x] I have the latest version of fzf
- [x] I have searched through the existing issues

## Info

- OS
- [x] Linux
- Shell
- [x] zsh

## Problem / Steps to reproduce

When wrapping is set, I want you to be able to automatically adjust the height of the preview window by the length of the inputted characters.
I don't want to show margins.

### reproduce

```shell
echo aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa | \
fzf --height 50% --preview "echo {}" --preview-window=up:30%:wrap
```

### argument example)

```shell
echo aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa | \
fzf --height 50% --preview "echo {}" --preview-window=up:fitwrap
```

### actual behavior


### expected behavior


Start by tracing fzf's --preview-window handling, especially the existing wrap and percentage-height behavior, using the reproduction command as the baseline. Done means a fitwrap-style option adjusts the preview height to wrapped input without leaving unwanted margins, while the existing preview-window behavior remains intact.

Written by the indexing model from the issue text.