Yazi hardening

[aspasia-patron]

I yazi should disable PDF previews by default, and ideally replace imagemagick and 7-zip especially with something safer, given how wild the level of vulnerabilities in 7-zip are.

[sxyazi]

Currently, there are no plans to disable PDF support by default, as having it available out-of-the-box is important for many users. However, it might be worthwhile to open a poll to collect inputs from the community.

#2611 explores the possibility of replacing ImageMagick, but so far, no suitable alternative has been found.

As for 7-zip, there is currently no alternative that matches its level (in terms of supported formats and performance). ouch might be an option to consider in the future, but for now, its preview performance is far inferior to 7-zip as I measured.